From 7a0d30d4468d5806fb2e6a7093689b1a550f9147 Mon Sep 17 00:00:00 2001
From: Antonin Houska <ah@cybertec.at>
Date: Tue, 27 Jan 2026 11:48:40 +0100
Subject: [PATCH v33 4/5] Add CONCURRENTLY option to REPACK command.

The REPACK command copies the relation data into a new file, creates new
indexes and eventually swaps the files. To make sure that the old file does
not change during the copying, the relation is locked in an exclusive mode,
which prevents applications from both reading and writing. (To keep the data
consistent, we'd only need to prevent the applications from writing, but even
reading needs to be blocked before we can swap the files - otherwise some
applications could continue using the old file. Since we should not request a
stronger lock without releasing the weaker one first, we acquire the exclusive
lock in the beginning and keep it till the end of the processing.)

This patch introduces an alternative workflow, which only requires the
exclusive lock when the relation (and index) files are being swapped.
(Supposedly, the swapping should be pretty fast.) On the other hand, when we
copy the data to the new file, we allow applications to read from the relation
and even to write to it.

First, we scan the relation using a "historic snapshot", and insert all the
tuples satisfying this snapshot into the new file.

Second, logical decoding is used to capture the data changes done by
applications during the copying (i.e. changes that do not satisfy the historic
snapshot mentioned above), and those are applied to the new file before we
acquire the exclusive lock that we need to swap the files. (Of course, more
data changes can take place while we are waiting for the lock - these will be
applied to the new file after we have acquired the lock, before we swap the
files.)

Since the logical decoding system, during its startup, waits until all the
transactions which already have XID assigned have finished, there is a risk of
deadlock if a transaction that already changed anything in the database tries
to acquire a conflicting lock on the table REPACK CONCURRENTLY is working
on. As an example, consider transaction running CREATE INDEX command on the
table that is being REPACKed CONCURRENTLY. On the other hand, DML commands
(INSERT, UPDATE, DELETE) are not a problem as their lock does not conflict
with REPACK CONCURRENTLY.

The current approach is that we accept the risk. If we tried to avoid it, it'd
be necessary to unlock the table before the logical decoding is setup and lock
it again afterwards. Such temporary unlocking would imply re-checking if the
table still meets all the requirements for REPACK CONCURRENTLY.

Like the existing implementation of REPACK, the variant with the CONCURRENTLY
option also requires an extra space for the new relation and index files
(which coexist with the old files for some time). In addition, the
CONCURRENTLY option might introduce a lag in releasing WAL segments for
archiving / recycling. This is due to the decoding of the data changes done by
applications concurrently. When copying the table contents into the new file,
we check the lag periodically. If it exceeds the size of a WAL segment, we
decode all the available WAL before resuming the copying. (Of course, the
changes are not applied until the whole table contents is copied.) A
background worker might be a better approach for the decoding - let's consider
implementing it in the future.

The WAL records produced by running DML commands on the new relation do not
contain enough information to be processed by the logical decoding system. All
we need from the new relation is the file (relfilenode), while the actual
relation is eventually dropped. Thus there is no point in replaying the DMLs
anywhere.
---
 doc/src/sgml/monitoring.sgml                  |   37 +-
 doc/src/sgml/mvcc.sgml                        |   12 +-
 doc/src/sgml/ref/repack.sgml                  |  129 +-
 src/Makefile                                  |    1 +
 src/backend/access/heap/heapam.c              |   34 +-
 src/backend/access/heap/heapam_handler.c      |  259 ++-
 src/backend/access/heap/rewriteheap.c         |    6 +-
 src/backend/catalog/system_views.sql          |   19 +-
 src/backend/commands/cluster.c                | 1641 +++++++++++++++--
 src/backend/commands/matview.c                |    2 +-
 src/backend/commands/tablecmds.c              |    1 +
 src/backend/commands/vacuum.c                 |   12 +-
 src/backend/meson.build                       |    1 +
 src/backend/replication/logical/decode.c      |   37 +-
 src/backend/replication/logical/snapbuild.c   |   21 +
 .../replication/pgoutput_repack/Makefile      |   32 +
 .../replication/pgoutput_repack/meson.build   |   18 +
 .../pgoutput_repack/pgoutput_repack.c         |  239 +++
 .../storage/lmgr/generate-lwlocknames.pl      |    2 +-
 src/backend/utils/time/snapmgr.c              |    3 +-
 src/bin/psql/tab-complete.in.c                |    4 +-
 src/include/access/heapam.h                   |    5 +-
 src/include/access/heapam_xlog.h              |    2 +
 src/include/access/tableam.h                  |   10 +
 src/include/commands/cluster.h                |   88 +-
 src/include/commands/progress.h               |   17 +-
 src/include/replication/snapbuild.h           |    1 +
 src/include/storage/lockdefs.h                |    4 +-
 src/include/utils/snapmgr.h                   |    2 +
 src/test/modules/injection_points/Makefile    |    2 +
 .../injection_points/expected/repack.out      |  113 ++
 .../expected/repack_toast.out                 |   64 +
 src/test/modules/injection_points/meson.build |    2 +
 .../injection_points/specs/repack.spec        |  142 ++
 .../injection_points/specs/repack_toast.spec  |  105 ++
 src/test/regress/expected/rules.out           |   19 +-
 src/tools/pgindent/typedefs.list              |    5 +
 37 files changed, 2829 insertions(+), 262 deletions(-)
 create mode 100644 src/backend/replication/pgoutput_repack/Makefile
 create mode 100644 src/backend/replication/pgoutput_repack/meson.build
 create mode 100644 src/backend/replication/pgoutput_repack/pgoutput_repack.c
 create mode 100644 src/test/modules/injection_points/expected/repack.out
 create mode 100644 src/test/modules/injection_points/expected/repack_toast.out
 create mode 100644 src/test/modules/injection_points/specs/repack.spec
 create mode 100644 src/test/modules/injection_points/specs/repack_toast.spec

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 71c92ed53ef..ec97197461a 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -6239,14 +6239,35 @@ FROM pg_stat_get_backend_idset() AS backendid;
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>heap_tuples_written</structfield> <type>bigint</type>
+       <structfield>heap_tuples_inserted</structfield> <type>bigint</type>
       </para>
       <para>
-       Number of heap tuples written.
+       Number of heap tuples inserted.
        This counter only advances when the phase is
        <literal>seq scanning heap</literal>,
-       <literal>index scanning heap</literal>
-       or <literal>writing new heap</literal>.
+       <literal>index scanning heap</literal>,
+       <literal>writing new heap</literal>
+       or <literal>catch-up</literal>.
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>heap_tuples_updated</structfield> <type>bigint</type>
+      </para>
+      <para>
+       Number of heap tuples updated.
+       This counter only advances when the phase is <literal>catch-up</literal>.
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>heap_tuples_deleted</structfield> <type>bigint</type>
+      </para>
+      <para>
+       Number of heap tuples deleted.
+       This counter only advances when the phase is <literal>catch-up</literal>.
       </para></entry>
      </row>
 
@@ -6327,6 +6348,14 @@ FROM pg_stat_get_backend_idset() AS backendid;
        <command>REPACK</command> is currently writing the new heap.
      </entry>
     </row>
+    <row>
+     <entry><literal>catch-up</literal></entry>
+     <entry>
+       <command>REPACK CONCURRENTLY</command> is currently processing the DML
+       commands that other transactions executed during any of the preceding
+       phases.
+     </entry>
+    </row>
     <row>
      <entry><literal>swapping relation files</literal></entry>
      <entry>
diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml
index 049ee75a4ba..0f5c34af542 100644
--- a/doc/src/sgml/mvcc.sgml
+++ b/doc/src/sgml/mvcc.sgml
@@ -1833,15 +1833,17 @@ SELECT pg_advisory_lock(q.id) FROM
    <title>Caveats</title>
 
    <para>
-    Some DDL commands, currently only <link linkend="sql-truncate"><command>TRUNCATE</command></link> and the
-    table-rewriting forms of <link linkend="sql-altertable"><command>ALTER TABLE</command></link>, are not
+    Some commands, currently only <link linkend="sql-truncate"><command>TRUNCATE</command></link>, the
+    table-rewriting forms of <link linkend="sql-altertable"><command>ALTER
+    TABLE</command></link> and <command>REPACK</command> with
+    the <literal>CONCURRENTLY</literal> option, are not
     MVCC-safe.  This means that after the truncation or rewrite commits, the
     table will appear empty to concurrent transactions, if they are using a
-    snapshot taken before the DDL command committed.  This will only be an
+    snapshot taken before the command committed.  This will only be an
     issue for a transaction that did not access the table in question
-    before the DDL command started &mdash; any transaction that has done so
+    before the command started &mdash; any transaction that has done so
     would hold at least an <literal>ACCESS SHARE</literal> table lock,
-    which would block the DDL command until that transaction completes.
+    which would block the truncating or rewriting command until that transaction completes.
     So these commands will not cause any apparent inconsistency in the
     table contents for successive queries on the target table, but they
     could cause visible inconsistency between the contents of the target
diff --git a/doc/src/sgml/ref/repack.sgml b/doc/src/sgml/ref/repack.sgml
index 61d5c2cdef1..30c43c49069 100644
--- a/doc/src/sgml/ref/repack.sgml
+++ b/doc/src/sgml/ref/repack.sgml
@@ -28,6 +28,7 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
 
     VERBOSE [ <replaceable class="parameter">boolean</replaceable> ]
     ANALYZE [ <replaceable class="parameter">boolean</replaceable> ]
+    CONCURRENTLY [ <replaceable class="parameter">boolean</replaceable> ]
 
 <phrase>and <replaceable class="parameter">table_and_columns</replaceable> is:</phrase>
 
@@ -54,7 +55,8 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
    processes every table and materialized view in the current database that
    the current user has the <literal>MAINTAIN</literal> privilege on. This
    form of <command>REPACK</command> cannot be executed inside a transaction
-   block.
+   block.  Also, this form is not allowed if
+   the <literal>CONCURRENTLY</literal> option is used.
   </para>
 
   <para>
@@ -67,7 +69,8 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
    When a table is being repacked, an <literal>ACCESS EXCLUSIVE</literal> lock
    is acquired on it. This prevents any other database operations (both reads
    and writes) from operating on the table until the <command>REPACK</command>
-   is finished.
+   is finished. If you want to keep the table accessible during the repacking,
+   consider using the <literal>CONCURRENTLY</literal> option.
   </para>
 
   <refsect2 id="sql-repack-notes-on-clustering" xreflabel="Notes on Clustering">
@@ -195,6 +198,128 @@ REPACK [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] USING
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>CONCURRENTLY</literal></term>
+    <listitem>
+     <para>
+      Allow other transactions to use the table while it is being repacked.
+     </para>
+
+     <para>
+      Internally, <command>REPACK</command> copies the contents of the table
+      (ignoring dead tuples) into a new file, sorted by the specified index,
+      and also creates a new file for each index. Then it swaps the old and
+      new files for the table and all the indexes, and deletes the old
+      files. The <literal>ACCESS EXCLUSIVE</literal> lock is needed to make
+      sure that the old files do not change during the processing because the
+      changes would get lost due to the swap.
+     </para>
+
+     <para>
+      With the <literal>CONCURRENTLY</literal> option, the <literal>ACCESS
+      EXCLUSIVE</literal> lock is only acquired to swap the table and index
+      files. The data changes that took place during the creation of the new
+      table and index files are captured using logical decoding
+      (<xref linkend="logicaldecoding"/>) and applied before
+      the <literal>ACCESS EXCLUSIVE</literal> lock is requested. Thus the lock
+      is typically held only for the time needed to swap the files, which
+      should be pretty short. However, the time might still be noticeable if
+      too many data changes have been done to the table while
+      <command>REPACK</command> was waiting for the lock: those changes must
+      be processed just before the files are swapped, while the
+      <literal>ACCESS EXCLUSIVE</literal> lock is being held.
+     </para>
+
+     <para>
+      Note that <command>REPACK</command> with the
+      <literal>CONCURRENTLY</literal> option does not try to order the rows
+      inserted into the table after the repacking started. Also
+      note <command>REPACK</command> might fail to complete due to DDL
+      commands executed on the table by other transactions during the
+      repacking.
+     </para>
+
+     <note>
+      <para>
+       In addition to the temporary space requirements explained in
+       <xref linkend="sql-repack-notes-on-resources"/>,
+       the <literal>CONCURRENTLY</literal> option can add to the usage of
+       temporary space a bit more. The reason is that other transactions can
+       perform DML operations which cannot be applied to the new file until
+       <command>REPACK</command> has copied all the tuples from the old
+       file. Thus the tuples inserted into the old file during the copying are
+       also stored separately in a temporary file, so they can eventually be
+       applied to the new file.
+      </para>
+
+      <para>
+       Furthermore, the data changes performed during the copying are
+       extracted from <link linkend="wal">write-ahead log</link> (WAL), and
+       this extraction (decoding) only takes place when certain amount of WAL
+       has been written. Therefore, WAL removal can be delayed by this
+       threshold. Currently the threshold is equal to the value of
+       the <link linkend="guc-wal-segment-size"><varname>wal_segment_size</varname></link>
+       configuration parameter.
+      </para>
+     </note>
+
+     <para>
+      The <literal>CONCURRENTLY</literal> option cannot be used in the
+      following cases:
+
+      <itemizedlist>
+       <listitem>
+        <para>
+          The table is <literal>UNLOGGED</literal>.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+          The table is partitioned.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+          The table is a system catalog or a <acronym>TOAST</acronym> table.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+         <command>REPACK</command> is executed inside a transaction block.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+          The <link linkend="guc-wal-level"><varname>wal_level</varname></link>
+          configuration parameter is less than <literal>logical</literal>.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+         The <link linkend="guc-max-replication-slots"><varname>max_replication_slots</varname></link>
+         configuration parameter does not allow for creation of an additional
+         replication slot.
+        </para>
+       </listitem>
+      </itemizedlist>
+     </para>
+
+     <warning>
+      <para>
+       <command>REPACK</command> with the <literal>CONCURRENTLY</literal>
+       option is not MVCC-safe, see <xref linkend="mvcc-caveats"/> for
+       details.
+      </para>
+     </warning>
+
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>VERBOSE</literal></term>
     <listitem>
diff --git a/src/Makefile b/src/Makefile
index 2f31a2f20a7..b18c9a14ffa 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -23,6 +23,7 @@ SUBDIRS = \
 	interfaces \
 	backend/replication/libpqwalreceiver \
 	backend/replication/pgoutput \
+	backend/replication/pgoutput_repack \
 	fe_utils \
 	bin \
 	pl \
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 3004964ab7f..a89a456135d 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -60,7 +60,8 @@ static HeapTuple heap_prepare_insert(Relation relation, HeapTuple tup,
 static XLogRecPtr log_heap_update(Relation reln, Buffer oldbuf,
 								  Buffer newbuf, HeapTuple oldtup,
 								  HeapTuple newtup, HeapTuple old_key_tuple,
-								  bool all_visible_cleared, bool new_all_visible_cleared);
+								  bool all_visible_cleared, bool new_all_visible_cleared,
+								  bool walLogical);
 #ifdef USE_ASSERT_CHECKING
 static void check_lock_if_inplace_updateable_rel(Relation relation,
 												 const ItemPointerData *otid,
@@ -2841,7 +2842,7 @@ xmax_infomask_changed(uint16 new_infomask, uint16 old_infomask)
 TM_Result
 heap_delete(Relation relation, const ItemPointerData *tid,
 			CommandId cid, Snapshot crosscheck, bool wait,
-			TM_FailureData *tmfd, bool changingPart)
+			TM_FailureData *tmfd, bool changingPart, bool walLogical)
 {
 	TM_Result	result;
 	TransactionId xid = GetCurrentTransactionId();
@@ -3088,7 +3089,8 @@ l1:
 	 * Compute replica identity tuple before entering the critical section so
 	 * we don't PANIC upon a memory allocation failure.
 	 */
-	old_key_tuple = ExtractReplicaIdentity(relation, &tp, true, &old_key_copied);
+	old_key_tuple = walLogical ?
+		ExtractReplicaIdentity(relation, &tp, true, &old_key_copied) : NULL;
 
 	/*
 	 * If this is the first possibly-multixact-able operation in the current
@@ -3178,6 +3180,15 @@ l1:
 				xlrec.flags |= XLH_DELETE_CONTAINS_OLD_KEY;
 		}
 
+		/*
+		 * Unlike UPDATE, DELETE is decoded even if there is no old key, so it
+		 * does not help to clear both XLH_DELETE_CONTAINS_OLD_TUPLE and
+		 * XLH_DELETE_CONTAINS_OLD_KEY. Thus we need an extra flag. TODO
+		 * Consider not decoding tuples w/o the old tuple/key instead.
+		 */
+		if (!walLogical)
+			xlrec.flags |= XLH_DELETE_NO_LOGICAL;
+
 		XLogBeginInsert();
 		XLogRegisterData(&xlrec, SizeOfHeapDelete);
 
@@ -3270,7 +3281,8 @@ simple_heap_delete(Relation relation, const ItemPointerData *tid)
 	result = heap_delete(relation, tid,
 						 GetCurrentCommandId(true), InvalidSnapshot,
 						 true /* wait for commit */ ,
-						 &tmfd, false /* changingPart */ );
+						 &tmfd, false,	/* changingPart */
+						 true /* walLogical */ );
 	switch (result)
 	{
 		case TM_SelfModified:
@@ -3311,7 +3323,7 @@ TM_Result
 heap_update(Relation relation, const ItemPointerData *otid, HeapTuple newtup,
 			CommandId cid, Snapshot crosscheck, bool wait,
 			TM_FailureData *tmfd, LockTupleMode *lockmode,
-			TU_UpdateIndexes *update_indexes)
+			TU_UpdateIndexes *update_indexes, bool walLogical)
 {
 	TM_Result	result;
 	TransactionId xid = GetCurrentTransactionId();
@@ -4204,7 +4216,8 @@ l2:
 								 newbuf, &oldtup, heaptup,
 								 old_key_tuple,
 								 all_visible_cleared,
-								 all_visible_cleared_new);
+								 all_visible_cleared_new,
+								 walLogical);
 		if (newbuf != buffer)
 		{
 			PageSetLSN(BufferGetPage(newbuf), recptr);
@@ -4562,7 +4575,8 @@ simple_heap_update(Relation relation, const ItemPointerData *otid, HeapTuple tup
 	result = heap_update(relation, otid, tup,
 						 GetCurrentCommandId(true), InvalidSnapshot,
 						 true /* wait for commit */ ,
-						 &tmfd, &lockmode, update_indexes);
+						 &tmfd, &lockmode, update_indexes,
+						 true /* walLogical */ );
 	switch (result)
 	{
 		case TM_SelfModified:
@@ -8918,7 +8932,8 @@ static XLogRecPtr
 log_heap_update(Relation reln, Buffer oldbuf,
 				Buffer newbuf, HeapTuple oldtup, HeapTuple newtup,
 				HeapTuple old_key_tuple,
-				bool all_visible_cleared, bool new_all_visible_cleared)
+				bool all_visible_cleared, bool new_all_visible_cleared,
+				bool walLogical)
 {
 	xl_heap_update xlrec;
 	xl_heap_header xlhdr;
@@ -8929,7 +8944,8 @@ log_heap_update(Relation reln, Buffer oldbuf,
 				suffixlen = 0;
 	XLogRecPtr	recptr;
 	Page		page = BufferGetPage(newbuf);
-	bool		need_tuple_data = RelationIsLogicallyLogged(reln);
+	bool		need_tuple_data = RelationIsLogicallyLogged(reln) &&
+		walLogical;
 	bool		init;
 	int			bufflags;
 
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 7d4b48e5a97..908f1ef66c6 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -33,6 +33,7 @@
 #include "catalog/index.h"
 #include "catalog/storage.h"
 #include "catalog/storage_xlog.h"
+#include "commands/cluster.h"
 #include "commands/progress.h"
 #include "executor/executor.h"
 #include "miscadmin.h"
@@ -309,7 +310,8 @@ heapam_tuple_delete(Relation relation, ItemPointer tid, CommandId cid,
 	 * the storage itself is cleaning the dead tuples by itself, it is the
 	 * time to call the index tuple deletion also.
 	 */
-	return heap_delete(relation, tid, cid, crosscheck, wait, tmfd, changingPart);
+	return heap_delete(relation, tid, cid, crosscheck, wait, tmfd, changingPart,
+					   true);
 }
 
 
@@ -328,7 +330,7 @@ heapam_tuple_update(Relation relation, ItemPointer otid, TupleTableSlot *slot,
 	tuple->t_tableOid = slot->tts_tableOid;
 
 	result = heap_update(relation, otid, tuple, cid, crosscheck, wait,
-						 tmfd, lockmode, update_indexes);
+						 tmfd, lockmode, update_indexes, true);
 	ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
 
 	/*
@@ -685,13 +687,15 @@ static void
 heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 								 Relation OldIndex, bool use_sort,
 								 TransactionId OldestXmin,
+								 Snapshot snapshot,
+								 LogicalDecodingContext *decoding_ctx,
 								 TransactionId *xid_cutoff,
 								 MultiXactId *multi_cutoff,
 								 double *num_tuples,
 								 double *tups_vacuumed,
 								 double *tups_recently_dead)
 {
-	RewriteState rwstate;
+	RewriteState rwstate = NULL;
 	IndexScanDesc indexScan;
 	TableScanDesc tableScan;
 	HeapScanDesc heapScan;
@@ -705,6 +709,8 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 	bool	   *isnull;
 	BufferHeapTupleTableSlot *hslot;
 	BlockNumber prev_cblock = InvalidBlockNumber;
+	bool		concurrent = snapshot != NULL;
+	XLogRecPtr	end_of_wal_prev = GetFlushRecPtr(NULL);
 
 	/* Remember if it's a system catalog */
 	is_system_catalog = IsSystemRelation(OldHeap);
@@ -720,9 +726,12 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 	values = palloc_array(Datum, natts);
 	isnull = palloc_array(bool, natts);
 
-	/* Initialize the rewrite operation */
-	rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin, *xid_cutoff,
-								 *multi_cutoff);
+	/*
+	 * Initialize the rewrite operation.
+	 */
+	if (!concurrent)
+		rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin,
+									 *xid_cutoff, *multi_cutoff);
 
 
 	/* Set up sorting if wanted */
@@ -737,6 +746,9 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 	 * Prepare to scan the OldHeap.  To ensure we see recently-dead tuples
 	 * that still need to be copied, we scan with SnapshotAny and use
 	 * HeapTupleSatisfiesVacuum for the visibility test.
+	 *
+	 * In the CONCURRENTLY case, we do regular MVCC visibility tests, using
+	 * the snapshot passed by the caller.
 	 */
 	if (OldIndex != NULL && !use_sort)
 	{
@@ -753,7 +765,9 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 
 		tableScan = NULL;
 		heapScan = NULL;
-		indexScan = index_beginscan(OldHeap, OldIndex, SnapshotAny, NULL, 0, 0);
+		indexScan = index_beginscan(OldHeap, OldIndex,
+									snapshot ? snapshot : SnapshotAny,
+									NULL, 0, 0);
 		index_rescan(indexScan, NULL, 0, NULL, 0);
 	}
 	else
@@ -762,7 +776,9 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 		pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
 									 PROGRESS_REPACK_PHASE_SEQ_SCAN_HEAP);
 
-		tableScan = table_beginscan(OldHeap, SnapshotAny, 0, (ScanKey) NULL);
+		tableScan = table_beginscan(OldHeap,
+									snapshot ? snapshot : SnapshotAny,
+									0, (ScanKey) NULL);
 		heapScan = (HeapScanDesc) tableScan;
 		indexScan = NULL;
 
@@ -838,83 +854,90 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 		buf = hslot->buffer;
 
 		/*
-		 * To be able to guarantee that we can set the hint bit, acquire an
-		 * exclusive lock on the old buffer. We need the hint bits, set in
-		 * heapam_relation_copy_for_cluster() -> HeapTupleSatisfiesVacuum(),
-		 * to be set, as otherwise reform_and_rewrite_tuple() ->
-		 * rewrite_heap_tuple() will get confused. Specifically,
-		 * rewrite_heap_tuple() checks for HEAP_XMAX_INVALID in the old tuple
-		 * to determine whether to check the old-to-new mapping hash table.
-		 *
-		 * It'd be better if we somehow could avoid setting hint bits on the
-		 * old page. One reason to use VACUUM FULL are very bloated tables -
-		 * rewriting most of the old table during VACUUM FULL doesn't exactly
-		 * help...
+		 * Regarding CONCURRENTLY, see the comments on MVCC snapshot above.
 		 */
-		LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
-
-		switch (HeapTupleSatisfiesVacuum(tuple, OldestXmin, buf))
+		if (!concurrent)
 		{
-			case HEAPTUPLE_DEAD:
-				/* Definitely dead */
-				isdead = true;
-				break;
-			case HEAPTUPLE_RECENTLY_DEAD:
-				*tups_recently_dead += 1;
-				/* fall through */
-			case HEAPTUPLE_LIVE:
-				/* Live or recently dead, must copy it */
-				isdead = false;
-				break;
-			case HEAPTUPLE_INSERT_IN_PROGRESS:
+			/*
+			 * To be able to guarantee that we can set the hint bit, acquire an
+			 * exclusive lock on the old buffer. We need the hint bits, set in
+			 * heapam_relation_copy_for_cluster() -> HeapTupleSatisfiesVacuum(),
+			 * to be set, as otherwise reform_and_rewrite_tuple() ->
+			 * rewrite_heap_tuple() will get confused. Specifically,
+			 * rewrite_heap_tuple() checks for HEAP_XMAX_INVALID in the old tuple
+			 * to determine whether to check the old-to-new mapping hash table.
+			 *
+			 * It'd be better if we somehow could avoid setting hint bits on the
+			 * old page. One reason to use VACUUM FULL are very bloated tables -
+			 * rewriting most of the old table during VACUUM FULL doesn't exactly
+			 * help...
+			 */
+			LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
 
-				/*
-				 * Since we hold exclusive lock on the relation, normally the
-				 * only way to see this is if it was inserted earlier in our
-				 * own transaction.  However, it can happen in system
-				 * catalogs, since we tend to release write lock before commit
-				 * there.  Give a warning if neither case applies; but in any
-				 * case we had better copy it.
-				 */
-				if (!is_system_catalog &&
-					!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple->t_data)))
-					elog(WARNING, "concurrent insert in progress within table \"%s\"",
-						 RelationGetRelationName(OldHeap));
-				/* treat as live */
-				isdead = false;
-				break;
-			case HEAPTUPLE_DELETE_IN_PROGRESS:
-
-				/*
-				 * Similar situation to INSERT_IN_PROGRESS case.
-				 */
-				if (!is_system_catalog &&
-					!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(tuple->t_data)))
-					elog(WARNING, "concurrent delete in progress within table \"%s\"",
-						 RelationGetRelationName(OldHeap));
-				/* treat as recently dead */
-				*tups_recently_dead += 1;
-				isdead = false;
-				break;
-			default:
-				elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
-				isdead = false; /* keep compiler quiet */
-				break;
-		}
-
-		LockBuffer(buf, BUFFER_LOCK_UNLOCK);
-
-		if (isdead)
-		{
-			*tups_vacuumed += 1;
-			/* heap rewrite module still needs to see it... */
-			if (rewrite_heap_dead_tuple(rwstate, tuple))
+			switch (HeapTupleSatisfiesVacuum(tuple, OldestXmin, buf))
 			{
-				/* A previous recently-dead tuple is now known dead */
-				*tups_vacuumed += 1;
-				*tups_recently_dead -= 1;
+				case HEAPTUPLE_DEAD:
+					/* Definitely dead */
+					isdead = true;
+					break;
+				case HEAPTUPLE_RECENTLY_DEAD:
+					*tups_recently_dead += 1;
+					/* fall through */
+				case HEAPTUPLE_LIVE:
+					/* Live or recently dead, must copy it */
+					isdead = false;
+					break;
+				case HEAPTUPLE_INSERT_IN_PROGRESS:
+
+					/*
+					 * As long as we hold exclusive lock on the relation,
+					 * normally the only way to see this is if it was inserted
+					 * earlier in our own transaction.  However, it can happen
+					 * in system catalogs, since we tend to release write lock
+					 * before commit there. Give a warning if neither case
+					 * applies; but in any case we had better copy it.
+					 */
+					if (!is_system_catalog &&
+						!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple->t_data)))
+						elog(WARNING, "concurrent insert in progress within table \"%s\"",
+							 RelationGetRelationName(OldHeap));
+					/* treat as live */
+					isdead = false;
+					break;
+				case HEAPTUPLE_DELETE_IN_PROGRESS:
+
+					/*
+					 * Similar situation to INSERT_IN_PROGRESS case.
+					 */
+					if (!is_system_catalog &&
+						!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(tuple->t_data)))
+						elog(WARNING, "concurrent delete in progress within table \"%s\"",
+							 RelationGetRelationName(OldHeap));
+					/* treat as recently dead */
+					*tups_recently_dead += 1;
+					isdead = false;
+					break;
+				default:
+					elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result");
+					isdead = false; /* keep compiler quiet */
+					break;
+			}
+
+			LockBuffer(buf, BUFFER_LOCK_UNLOCK);
+
+			if (isdead)
+			{
+				*tups_vacuumed += 1;
+				/* heap rewrite module still needs to see it... */
+				if (rewrite_heap_dead_tuple(rwstate, tuple))
+				{
+					/* A previous recently-dead tuple is now known dead */
+					*tups_vacuumed += 1;
+					*tups_recently_dead -= 1;
+				}
+
+				continue;
 			}
-			continue;
 		}
 
 		*num_tuples += 1;
@@ -933,7 +956,7 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 		{
 			const int	ct_index[] = {
 				PROGRESS_REPACK_HEAP_TUPLES_SCANNED,
-				PROGRESS_REPACK_HEAP_TUPLES_WRITTEN
+				PROGRESS_REPACK_HEAP_TUPLES_INSERTED
 			};
 			int64		ct_val[2];
 
@@ -948,6 +971,31 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 			ct_val[1] = *num_tuples;
 			pgstat_progress_update_multi_param(2, ct_index, ct_val);
 		}
+
+		/*
+		 * Process the WAL produced by the load, as well as by other
+		 * transactions, so that the replication slot can advance and WAL does
+		 * not pile up. Use wal_segment_size as a threshold so that we do not
+		 * introduce the decoding overhead too often.
+		 *
+		 * Of course, we must not apply the changes until the initial load has
+		 * completed.
+		 *
+		 * Note that our insertions into the new table should not be decoded
+		 * as we (intentionally) do not write the logical decoding specific
+		 * information to WAL.
+		 */
+		if (concurrent)
+		{
+			XLogRecPtr	end_of_wal;
+
+			end_of_wal = GetFlushRecPtr(NULL);
+			if ((end_of_wal - end_of_wal_prev) > wal_segment_size)
+			{
+				repack_decode_concurrent_changes(decoding_ctx, end_of_wal);
+				end_of_wal_prev = end_of_wal;
+			}
+		}
 	}
 
 	if (indexScan != NULL)
@@ -991,15 +1039,32 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
 									 values, isnull,
 									 rwstate);
 			/* Report n_tuples */
-			pgstat_progress_update_param(PROGRESS_REPACK_HEAP_TUPLES_WRITTEN,
+			pgstat_progress_update_param(PROGRESS_REPACK_HEAP_TUPLES_INSERTED,
 										 n_tuples);
+
+			/*
+			 * Try to keep the amount of not-yet-decoded WAL small, like
+			 * above.
+			 */
+			if (concurrent)
+			{
+				XLogRecPtr	end_of_wal;
+
+				end_of_wal = GetFlushRecPtr(NULL);
+				if ((end_of_wal - end_of_wal_prev) > wal_segment_size)
+				{
+					repack_decode_concurrent_changes(decoding_ctx, end_of_wal);
+					end_of_wal_prev = end_of_wal;
+				}
+			}
 		}
 
 		tuplesort_end(tuplesort);
 	}
 
 	/* Write out any remaining tuples, and fsync if needed */
-	end_heap_rewrite(rwstate);
+	if (rwstate)
+		end_heap_rewrite(rwstate);
 
 	/* Clean up */
 	pfree(values);
@@ -2390,6 +2455,10 @@ heapam_scan_sample_next_tuple(TableScanDesc scan, SampleScanState *scanstate,
  * SET WITHOUT OIDS.
  *
  * So, we must reconstruct the tuple from component Datums.
+ *
+ * If rwstate=NULL, use simple_heap_insert() instead of rewriting - in that
+ * case we still need to deform/form the tuple. TODO Shouldn't we rename the
+ * function, as might not do any rewrite?
  */
 static void
 reform_and_rewrite_tuple(HeapTuple tuple,
@@ -2412,8 +2481,28 @@ reform_and_rewrite_tuple(HeapTuple tuple,
 
 	copiedTuple = heap_form_tuple(newTupDesc, values, isnull);
 
-	/* The heap rewrite module does the rest */
-	rewrite_heap_tuple(rwstate, tuple, copiedTuple);
+	if (rwstate)
+		/* The heap rewrite module does the rest */
+		rewrite_heap_tuple(rwstate, tuple, copiedTuple);
+	else
+	{
+		/*
+		 * Insert tuple when processing REPACK CONCURRENTLY.
+		 *
+		 * rewriteheap.c is not used in the CONCURRENTLY case because it'd be
+		 * difficult to do the same in the catch-up phase (as the logical
+		 * decoding does not provide us with sufficient visibility
+		 * information). Thus we must use heap_insert() both during the
+		 * catch-up and here.
+		 *
+		 * The following is like simple_heap_insert() except that we pass the
+		 * flag to skip logical decoding: as soon as REPACK CONCURRENTLY swaps
+		 * the relation files, it drops this relation, so no logical
+		 * replication subscription should need the data.
+		 */
+		heap_insert(NewHeap, copiedTuple, GetCurrentCommandId(true),
+					HEAP_INSERT_NO_LOGICAL, NULL);
+	}
 
 	heap_freetuple(copiedTuple);
 }
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 77fd48eb59e..96be7684660 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -620,9 +620,9 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
 		int			options = HEAP_INSERT_SKIP_FSM;
 
 		/*
-		 * While rewriting the heap for VACUUM FULL / CLUSTER, make sure data
-		 * for the TOAST table are not logically decoded.  The main heap is
-		 * WAL-logged as XLOG FPI records, which are not logically decoded.
+		 * While rewriting the heap for REPACK, make sure data for the TOAST
+		 * table are not logically decoded.  The main heap is WAL-logged as
+		 * XLOG FPI records, which are not logically decoded.
 		 */
 		options |= HEAP_INSERT_NO_LOGICAL;
 
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 3f05ba3083a..d79eab5670c 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1298,16 +1298,19 @@ CREATE VIEW pg_stat_progress_repack AS
                       WHEN 2 THEN 'index scanning heap'
                       WHEN 3 THEN 'sorting tuples'
                       WHEN 4 THEN 'writing new heap'
-                      WHEN 5 THEN 'swapping relation files'
-                      WHEN 6 THEN 'rebuilding index'
-                      WHEN 7 THEN 'performing final cleanup'
+                      WHEN 5 THEN 'catch-up'
+                      WHEN 6 THEN 'swapping relation files'
+                      WHEN 7 THEN 'rebuilding index'
+                      WHEN 8 THEN 'performing final cleanup'
                       END AS phase,
         CAST(S.param3 AS oid) AS repack_index_relid,
         S.param4 AS heap_tuples_scanned,
-        S.param5 AS heap_tuples_written,
-        S.param6 AS heap_blks_total,
-        S.param7 AS heap_blks_scanned,
-        S.param8 AS index_rebuild_count
+        S.param5 AS heap_tuples_inserted,
+        S.param6 AS heap_tuples_updated,
+        S.param7 AS heap_tuples_deleted,
+        S.param8 AS heap_blks_total,
+        S.param9 AS heap_blks_scanned,
+        S.param10 AS index_rebuild_count
     FROM pg_stat_get_progress_info('REPACK') AS S
         LEFT JOIN pg_database D ON S.datid = D.oid;
 
@@ -1325,7 +1328,7 @@ CREATE VIEW pg_stat_progress_cluster AS
         phase,
         repack_index_relid AS cluster_index_relid,
         heap_tuples_scanned,
-        heap_tuples_written,
+        heap_tuples_inserted + heap_tuples_updated AS heap_tuples_written,
         heap_blks_total,
         heap_blks_scanned,
         index_rebuild_count
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index e19675a6d05..03ccf10b782 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -1,8 +1,23 @@
 /*-------------------------------------------------------------------------
  *
  * cluster.c
- *	  CLUSTER a table on an index.  This is now also used for VACUUM FULL and
- *	  REPACK.
+ *		Implementation of REPACK [CONCURRENTLY], also known as CLUSTER and
+ *		VACUUM FULL.
+ *
+ * There are two somewhat different ways to rewrite a table.  In non-
+ * concurrent mode, it's easy: take AccessExclusiveLock, create a new
+ * transient relation, copy the tuples over to the relfilenode of the new
+ * relation, swap the relfilenodes, then drop the old relation.
+ *
+ * In concurrent mode, we lock the table with only ShareUpdateExclusiveLock,
+ * then do an initial copy as above.  However, while the tuples are being
+ * copied, concurrent transactions could modify the table. To cope with those
+ * changes, we rely on logical decoding to obtain them from WAL.  The changes
+ * are accumulated in a tuplestore.  Once the initial copy is complete, we
+ * read the changes from the tuplestore and re-apply them on the new heap.
+ * Then we upgrade our ShareUpdateExclusiveLock to AccessExclusiveLock and
+ * swap the relfilenodes.  This way, the time we hold a strong lock on the
+ * table is much reduced, and the bloat is eliminated.
  *
  * There is hardly anything left of Paul Brown's original implementation...
  *
@@ -26,6 +41,10 @@
 #include "access/toast_internals.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "access/xlog.h"
+#include "access/xlog_internal.h"
+#include "access/xloginsert.h"
+#include "access/xlogutils.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
 #include "catalog/heap.h"
@@ -33,6 +52,7 @@
 #include "catalog/namespace.h"
 #include "catalog/objectaccess.h"
 #include "catalog/pg_am.h"
+#include "catalog/pg_control.h"
 #include "catalog/pg_inherits.h"
 #include "catalog/toasting.h"
 #include "commands/cluster.h"
@@ -40,15 +60,21 @@
 #include "commands/progress.h"
 #include "commands/tablecmds.h"
 #include "commands/vacuum.h"
+#include "executor/executor.h"
 #include "miscadmin.h"
 #include "optimizer/optimizer.h"
 #include "pgstat.h"
+#include "replication/decode.h"
+#include "replication/logical.h"
+#include "replication/snapbuild.h"
 #include "storage/bufmgr.h"
+#include "storage/ipc.h"
 #include "storage/lmgr.h"
 #include "storage/predicate.h"
 #include "utils/acl.h"
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
+#include "utils/injection_point.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
@@ -68,12 +94,62 @@ typedef struct
 	Oid			indexOid;
 } RelToCluster;
 
+/*
+ * The following definitions are used for concurrent processing.
+ */
+
+/*
+ * The locators are used to avoid logical decoding of data that we do not need
+ * for our table.
+ */
+static RelFileLocator repacked_rel_locator = {.relNumber = InvalidOid};
+static RelFileLocator repacked_rel_toast_locator = {.relNumber = InvalidOid};
+
+/*
+ * Everything we need to call ExecInsertIndexTuples().
+ */
+typedef struct IndexInsertState
+{
+	ResultRelInfo *rri;
+	EState	   *estate;
+} IndexInsertState;
+
+/* The WAL segment being decoded. */
+static XLogSegNo repack_current_segment = 0;
+
+/*
+ * Information needed to apply concurrent data changes.
+ */
+typedef struct ChangeDest
+{
+	/* The relation the changes are applied to. */
+	Relation	rel;
+
+	/*
+	 * The following is needed to find the existing tuple if the change is
+	 * UPDATE or DELETE. 'ident_key' should have all the fields except for
+	 * 'sk_argument' initialized.
+	 */
+	Relation	ident_index;
+	ScanKey		ident_key;
+	int			ident_key_nentries;
+
+	/* Needed to update indexes of rel_dst. */
+	IndexInsertState *iistate;
+} ChangeDest;
+
 static bool cluster_rel_recheck(RepackCommand cmd, Relation OldHeap,
-								Oid indexOid, Oid userid, int options);
-static void rebuild_relation(Relation OldHeap, Relation index, bool verbose);
+								Oid indexOid, Oid userid, LOCKMODE lmode,
+								int options);
+static void check_repack_concurrently_requirements(Relation rel);
+static void rebuild_relation(Relation OldHeap, Relation index, bool verbose,
+							 bool concurrent);
 static void copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex,
-							bool verbose, bool *pSwapToastByContent,
-							TransactionId *pFreezeXid, MultiXactId *pCutoffMulti);
+							Snapshot snapshot, LogicalDecodingContext *decoding_ctx,
+							bool verbose,
+							bool *pSwapToastByContent,
+							TransactionId *pFreezeXid,
+							MultiXactId *pCutoffMulti);
 static List *get_tables_to_repack(RepackCommand cmd, bool usingindex,
 								  MemoryContext permcxt);
 static List *get_tables_to_repack_partitioned(RepackCommand cmd,
@@ -81,13 +157,50 @@ static List *get_tables_to_repack_partitioned(RepackCommand cmd,
 											  MemoryContext permcxt);
 static bool cluster_is_permitted_for_relation(RepackCommand cmd,
 											  Oid relid, Oid userid);
+
+static void begin_concurrent_repack(Relation rel);
+static void end_concurrent_repack(void);
+static LogicalDecodingContext *setup_logical_decoding(Oid relid);
+static HeapTuple get_changed_tuple(char *change);
+static void apply_concurrent_changes(RepackDecodingState *dstate,
+									 ChangeDest *dest);
+static void apply_concurrent_insert(Relation rel, HeapTuple tup,
+									IndexInsertState *iistate,
+									TupleTableSlot *index_slot);
+static void apply_concurrent_update(Relation rel, HeapTuple tup,
+									HeapTuple tup_target,
+									IndexInsertState *iistate,
+									TupleTableSlot *index_slot);
+static void apply_concurrent_delete(Relation rel, HeapTuple tup_target);
+static HeapTuple find_target_tuple(Relation rel, ChangeDest *dest,
+								   HeapTuple tup_key,
+								   TupleTableSlot *ident_slot);
+static void process_concurrent_changes(LogicalDecodingContext *decoding_ctx,
+									   XLogRecPtr end_of_wal,
+									   ChangeDest *dest);
+static IndexInsertState *get_index_insert_state(Relation relation,
+												Oid ident_index_id,
+												Relation *ident_index_p);
+static ScanKey build_identity_key(Oid ident_idx_oid, Relation rel_src,
+								  int *nentries);
+static void free_index_insert_state(IndexInsertState *iistate);
+static void cleanup_logical_decoding(LogicalDecodingContext *ctx);
+static void rebuild_relation_finish_concurrent(Relation NewHeap, Relation OldHeap,
+											   LogicalDecodingContext *decoding_ctx,
+											   TransactionId frozenXid,
+											   MultiXactId cutoffMulti);
+static List *build_new_indexes(Relation NewHeap, Relation OldHeap, List *OldIndexes);
 static Relation process_single_relation(RepackStmt *stmt,
+										LOCKMODE lockmode,
+										bool isTopLevel,
 										ClusterParams *params);
 static Oid	determine_clustered_index(Relation rel, bool usingindex,
 									  const char *indexname);
 static const char *RepackCommandAsString(RepackCommand cmd);
 
 
+#define REPL_PLUGIN_NAME   "pgoutput_repack"
+
 /*
  * The repack code allows for processing multiple tables at once. Because
  * of this, we cannot just run everything on a single transaction, or we
@@ -117,6 +230,7 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
 	ClusterParams params = {0};
 	Relation	rel = NULL;
 	MemoryContext repack_context;
+	LOCKMODE	lockmode;
 	List	   *rtcs;
 
 	/* Parse option list */
@@ -127,6 +241,16 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
 		else if (strcmp(opt->defname, "analyze") == 0 ||
 				 strcmp(opt->defname, "analyse") == 0)
 			params.options |= defGetBoolean(opt) ? CLUOPT_ANALYZE : 0;
+		else if (strcmp(opt->defname, "concurrently") == 0 &&
+				 defGetBoolean(opt))
+		{
+			if (stmt->command != REPACK_COMMAND_REPACK)
+				ereport(ERROR,
+						errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						errmsg("CONCURRENTLY option not supported for %s",
+							   RepackCommandAsString(stmt->command)));
+			params.options |= CLUOPT_CONCURRENT;
+		}
 		else
 			ereport(ERROR,
 					errcode(ERRCODE_SYNTAX_ERROR),
@@ -136,13 +260,25 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
 					parser_errposition(pstate, opt->location));
 	}
 
+	/*
+	 * Determine the lock mode expected by cluster_rel().
+	 *
+	 * In the exclusive case, we obtain AccessExclusiveLock right away to
+	 * avoid lock-upgrade hazard in the single-transaction case. In the
+	 * CONCURRENTLY case, the AccessExclusiveLock will only be used at the end
+	 * of processing, supposedly for very short time. Until then, we'll have
+	 * to unlock the relation temporarily, so there's no lock-upgrade hazard.
+	 */
+	lockmode = (params.options & CLUOPT_CONCURRENT) == 0 ?
+		AccessExclusiveLock : ShareUpdateExclusiveLock;
+
 	/*
 	 * If a single relation is specified, process it and we're done ... unless
 	 * the relation is a partitioned table, in which case we fall through.
 	 */
 	if (stmt->relation != NULL)
 	{
-		rel = process_single_relation(stmt, &params);
+		rel = process_single_relation(stmt, lockmode, isTopLevel, &params);
 		if (rel == NULL)
 			return;				/* all done */
 	}
@@ -157,10 +293,29 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
 				errmsg("cannot %s multiple tables", "REPACK (ANALYZE)"));
 
 	/*
-	 * By here, we know we are in a multi-table situation.  In order to avoid
-	 * holding locks for too long, we want to process each table in its own
-	 * transaction.  This forces us to disallow running inside a user
-	 * transaction block.
+	 * By here, we know we are in a multi-table situation.
+	 *
+	 * Concurrent processing is currently considered rather special (e.g. in
+	 * terms of resources consumed) so it is not performed in bulk.
+	 */
+	if (params.options & CLUOPT_CONCURRENT)
+	{
+		if (rel != NULL)
+		{
+			Assert(rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
+			ereport(ERROR,
+					errmsg("REPACK CONCURRENTLY not supported for partitioned tables"),
+					errhint("Consider running the command for individual partitions."));
+		}
+		else
+			ereport(ERROR,
+					errmsg("REPACK CONCURRENTLY requires explicit table name"));
+	}
+
+	/*
+	 * In order to avoid holding locks for too long, we want to process each
+	 * table in its own transaction.  This forces us to disallow running
+	 * inside a user transaction block.
 	 */
 	PreventInTransactionBlock(isTopLevel, RepackCommandAsString(stmt->command));
 
@@ -244,7 +399,7 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
 		 * Open the target table, coping with the case where it has been
 		 * dropped.
 		 */
-		rel = try_table_open(rtc->tableOid, AccessExclusiveLock);
+		rel = try_table_open(rtc->tableOid, lockmode);
 		if (rel == NULL)
 		{
 			CommitTransactionCommand();
@@ -255,7 +410,7 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
 		PushActiveSnapshot(GetTransactionSnapshot());
 
 		/* Process this table */
-		cluster_rel(stmt->command, rel, rtc->indexOid, &params);
+		cluster_rel(stmt->command, rel, rtc->indexOid, &params, isTopLevel);
 		/* cluster_rel closes the relation, but keeps lock */
 
 		PopActiveSnapshot();
@@ -284,22 +439,53 @@ ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel)
  * If indexOid is InvalidOid, the table will be rewritten in physical order
  * instead of index order.
  *
+ * Note that, in the concurrent case, the function releases the lock at some
+ * point, in order to get AccessExclusiveLock for the final steps (i.e. to
+ * swap the relation files). To make things simpler, the caller should expect
+ * OldHeap to be closed on return, regardless CLUOPT_CONCURRENT. (The
+ * AccessExclusiveLock is kept till the end of the transaction.)
+ *
  * 'cmd' indicates which command is being executed, to be used for error
  * messages.
  */
 void
 cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid,
-			ClusterParams *params)
+			ClusterParams *params, bool isTopLevel)
 {
 	Oid			tableOid = RelationGetRelid(OldHeap);
+	Relation	index;
+	LOCKMODE	lmode;
 	Oid			save_userid;
 	int			save_sec_context;
 	int			save_nestlevel;
 	bool		verbose = ((params->options & CLUOPT_VERBOSE) != 0);
 	bool		recheck = ((params->options & CLUOPT_RECHECK) != 0);
-	Relation	index;
+	bool		concurrent = ((params->options & CLUOPT_CONCURRENT) != 0);
 
-	Assert(CheckRelationLockedByMe(OldHeap, AccessExclusiveLock, false));
+	/*
+	 * The lock mode is AccessExclusiveLock for normal processing and
+	 * ShareUpdateExclusiveLock for concurrent processing (so that SELECT,
+	 * INSERT, UPDATE and DELETE commands work, but cluster_rel() cannot be
+	 * called concurrently for the same relation).
+	 */
+	lmode = !concurrent ? AccessExclusiveLock : ShareUpdateExclusiveLock;
+
+	/* There are specific requirements on concurrent processing. */
+	if (concurrent)
+	{
+		/*
+		 * Make sure we have no XID assigned, otherwise call of
+		 * setup_logical_decoding() can cause a deadlock.
+		 *
+		 * The existence of transaction block actually does not imply that XID
+		 * was already assigned, but it very likely is. We might want to check
+		 * the result of GetCurrentTransactionIdIfAny() instead, but that
+		 * would be less clear from user's perspective.
+		 */
+		PreventInTransactionBlock(isTopLevel, "REPACK (CONCURRENTLY)");
+
+		check_repack_concurrently_requirements(OldHeap);
+	}
 
 	/* Check for user-requested abort. */
 	CHECK_FOR_INTERRUPTS();
@@ -325,10 +511,13 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 	 * If this is a single-transaction CLUSTER, we can skip these tests. We
 	 * *must* skip the one on indisclustered since it would reject an attempt
 	 * to cluster a not-previously-clustered index.
+	 *
+	 * XXX move [some of] these comments to where the RECHECK flag is
+	 * determined?
 	 */
 	if (recheck &&
 		!cluster_rel_recheck(cmd, OldHeap, indexOid, save_userid,
-							 params->options))
+							 lmode, params->options))
 		goto out;
 
 	/*
@@ -343,6 +532,12 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 				errmsg("cannot run %s on a shared catalog",
 					   RepackCommandAsString(cmd)));
 
+	/*
+	 * The CONCURRENTLY case should have been rejected earlier because it does
+	 * not support system catalogs.
+	 */
+	Assert(!(OldHeap->rd_rel->relisshared && concurrent));
+
 	/*
 	 * Don't process temp tables of other backends ... their local buffer
 	 * manager is not going to cope.
@@ -363,7 +558,7 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 	if (OidIsValid(indexOid))
 	{
 		/* verify the index is good and lock it */
-		check_index_is_clusterable(OldHeap, indexOid, AccessExclusiveLock);
+		check_index_is_clusterable(OldHeap, indexOid, lmode);
 		/* also open it */
 		index = index_open(indexOid, NoLock);
 	}
@@ -398,7 +593,9 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 	if (OldHeap->rd_rel->relkind == RELKIND_MATVIEW &&
 		!RelationIsPopulated(OldHeap))
 	{
-		relation_close(OldHeap, AccessExclusiveLock);
+		if (index)
+			index_close(index, lmode);
+		relation_close(OldHeap, lmode);
 		goto out;
 	}
 
@@ -411,11 +608,34 @@ cluster_rel(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 	 * invalid, because we move tuples around.  Promote them to relation
 	 * locks.  Predicate locks on indexes will be promoted when they are
 	 * reindexed.
+	 *
+	 * During concurrent processing, the heap as well as its indexes stay in
+	 * operation, so we postpone this step until they are locked using
+	 * AccessExclusiveLock near the end of the processing.
 	 */
-	TransferPredicateLocksToHeapRelation(OldHeap);
+	if (!concurrent)
+		TransferPredicateLocksToHeapRelation(OldHeap);
 
 	/* rebuild_relation does all the dirty work */
-	rebuild_relation(OldHeap, index, verbose);
+	PG_TRY();
+	{
+		/*
+		 * For concurrent processing, make sure that our logical decoding
+		 * ignores data changes of other tables than the one we are
+		 * processing.
+		 */
+		if (concurrent)
+			begin_concurrent_repack(OldHeap);
+
+		rebuild_relation(OldHeap, index, verbose, concurrent);
+	}
+	PG_FINALLY();
+	{
+		if (concurrent)
+			end_concurrent_repack();
+	}
+	PG_END_TRY();
+
 	/* rebuild_relation closes OldHeap, and index if valid */
 
 out:
@@ -434,14 +654,14 @@ out:
  */
 static bool
 cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid,
-					Oid userid, int options)
+					Oid userid, LOCKMODE lmode, int options)
 {
 	Oid			tableOid = RelationGetRelid(OldHeap);
 
 	/* Check that the user still has privileges for the relation */
 	if (!cluster_is_permitted_for_relation(cmd, tableOid, userid))
 	{
-		relation_close(OldHeap, AccessExclusiveLock);
+		relation_close(OldHeap, lmode);
 		return false;
 	}
 
@@ -455,7 +675,7 @@ cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 	 */
 	if (RELATION_IS_OTHER_TEMP(OldHeap))
 	{
-		relation_close(OldHeap, AccessExclusiveLock);
+		relation_close(OldHeap, lmode);
 		return false;
 	}
 
@@ -466,7 +686,7 @@ cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 		 */
 		if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(indexOid)))
 		{
-			relation_close(OldHeap, AccessExclusiveLock);
+			relation_close(OldHeap, lmode);
 			return false;
 		}
 
@@ -477,7 +697,7 @@ cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid,
 		if ((options & CLUOPT_RECHECK_ISCLUSTERED) != 0 &&
 			!get_index_isclustered(indexOid))
 		{
-			relation_close(OldHeap, AccessExclusiveLock);
+			relation_close(OldHeap, lmode);
 			return false;
 		}
 	}
@@ -489,7 +709,7 @@ cluster_rel_recheck(RepackCommand cmd, Relation OldHeap, Oid indexOid,
  * Verify that the specified heap and index are valid to cluster on
  *
  * Side effect: obtains lock on the index.  The caller may
- * in some cases already have AccessExclusiveLock on the table, but
+ * in some cases already have a lock of the same strength on the table, but
  * not in all cases so we can't rely on the table-level lock for
  * protection here.
  */
@@ -619,17 +839,86 @@ mark_index_clustered(Relation rel, Oid indexOid, bool is_internal)
 }
 
 /*
- * rebuild_relation: rebuild an existing relation in index or physical order
- *
- * OldHeap: table to rebuild.
- * index: index to cluster by, or NULL to rewrite in physical order.
- *
- * On entry, heap and index (if one is given) must be open, and
- * AccessExclusiveLock held on them.
- * On exit, they are closed, but locks on them are not released.
+ * Check if the CONCURRENTLY option is legal for the relation.
  */
 static void
-rebuild_relation(Relation OldHeap, Relation index, bool verbose)
+check_repack_concurrently_requirements(Relation rel)
+{
+	char		relpersistence,
+				replident;
+	Oid			ident_idx;
+
+	/* Data changes in system relations are not logically decoded. */
+	if (IsCatalogRelation(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot repack relation \"%s\"",
+						RelationGetRelationName(rel)),
+				 errhint("REPACK CONCURRENTLY is not supported for catalog relations.")));
+
+	/*
+	 * reorderbuffer.c does not seem to handle processing of TOAST relation
+	 * alone.
+	 */
+	if (IsToastRelation(rel))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot repack relation \"%s\"",
+						RelationGetRelationName(rel)),
+				 errhint("REPACK CONCURRENTLY is not supported for TOAST relations, unless the main relation is repacked too.")));
+
+	relpersistence = rel->rd_rel->relpersistence;
+	if (relpersistence != RELPERSISTENCE_PERMANENT)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("cannot repack relation \"%s\"",
+						RelationGetRelationName(rel)),
+				 errhint("REPACK CONCURRENTLY is only allowed for permanent relations.")));
+
+	/* With NOTHING, WAL does not contain the old tuple. */
+	replident = rel->rd_rel->relreplident;
+	if (replident == REPLICA_IDENTITY_NOTHING)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("cannot repack relation \"%s\"",
+						RelationGetRelationName(rel)),
+				 errhint("Relation \"%s\" has insufficient replication identity.",
+						 RelationGetRelationName(rel))));
+
+	/*
+	 * Identity index is not set if the replica identity is FULL, but PK might
+	 * exist in such a case.
+	 */
+	ident_idx = RelationGetReplicaIndex(rel);
+	if (!OidIsValid(ident_idx) && OidIsValid(rel->rd_pkindex))
+		ident_idx = rel->rd_pkindex;
+	if (!OidIsValid(ident_idx))
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("cannot process relation \"%s\"",
+						RelationGetRelationName(rel)),
+				 errhint("Relation \"%s\" has no identity index.",
+						 RelationGetRelationName(rel))));
+}
+
+
+/*
+ * rebuild_relation: rebuild an existing relation in index or physical order
+ *
+ * OldHeap: table to rebuild.  See cluster_rel() for comments on the required
+ * lock strength.
+ *
+ * index: index to cluster by, or NULL to rewrite in physical order.
+ *
+ * On entry, heap and index (if one is given) must be open, and the
+ * appropriate lock held on them -- AccessExclusiveLock for exclusive
+ * processing and ShareUpdateExclusiveLock for concurrent processing.
+ *
+ * On exit, they are closed, but still locked with AccessExclusiveLock.
+ * (The function handles the lock upgrade if 'concurrent' is true.)
+ */
+static void
+rebuild_relation(Relation OldHeap, Relation index, bool verbose, bool concurrent)
 {
 	Oid			tableOid = RelationGetRelid(OldHeap);
 	Oid			accessMethod = OldHeap->rd_rel->relam;
@@ -637,13 +926,38 @@ rebuild_relation(Relation OldHeap, Relation index, bool verbose)
 	Oid			OIDNewHeap;
 	Relation	NewHeap;
 	char		relpersistence;
-	bool		is_system_catalog;
 	bool		swap_toast_by_content;
 	TransactionId frozenXid;
 	MultiXactId cutoffMulti;
+	LogicalDecodingContext *decoding_ctx = NULL;
+	Snapshot	snapshot = NULL;
+#if USE_ASSERT_CHECKING
+	LOCKMODE	lmode;
 
-	Assert(CheckRelationLockedByMe(OldHeap, AccessExclusiveLock, false) &&
-		   (index == NULL || CheckRelationLockedByMe(index, AccessExclusiveLock, false)));
+	lmode = concurrent ? ShareUpdateExclusiveLock : AccessExclusiveLock;
+
+	Assert(CheckRelationLockedByMe(OldHeap, lmode, false));
+	Assert(index == NULL || CheckRelationLockedByMe(index, lmode, false));
+#endif
+
+	if (concurrent)
+	{
+		/*
+		 * Prepare to capture the concurrent data changes.
+		 *
+		 * Note that this call waits for all transactions with XID already
+		 * assigned to finish. If some of those transactions is waiting for a
+		 * lock conflicting with ShareUpdateExclusiveLock on our table (e.g.
+		 * it runs CREATE INDEX), we can end up in a deadlock. Not sure this
+		 * risk is worth unlocking/locking the table (and its clustering
+		 * index) and checking again if its still eligible for REPACK
+		 * CONCURRENTLY.
+		 */
+		decoding_ctx = setup_logical_decoding(tableOid);
+
+		snapshot = SnapBuildInitialSnapshotForRepack(decoding_ctx->snapshot_builder);
+		PushActiveSnapshot(snapshot);
+	}
 
 	/* for CLUSTER or REPACK USING INDEX, mark the index as the one to use */
 	if (index != NULL)
@@ -651,7 +965,6 @@ rebuild_relation(Relation OldHeap, Relation index, bool verbose)
 
 	/* Remember info about rel before closing OldHeap */
 	relpersistence = OldHeap->rd_rel->relpersistence;
-	is_system_catalog = IsSystemRelation(OldHeap);
 
 	/*
 	 * Create the transient table that will receive the re-ordered data.
@@ -667,30 +980,61 @@ rebuild_relation(Relation OldHeap, Relation index, bool verbose)
 	NewHeap = table_open(OIDNewHeap, NoLock);
 
 	/* Copy the heap data into the new table in the desired order */
-	copy_table_data(NewHeap, OldHeap, index, verbose,
+	copy_table_data(NewHeap, OldHeap, index, snapshot, decoding_ctx, verbose,
 					&swap_toast_by_content, &frozenXid, &cutoffMulti);
 
+	/* The historic snapshot won't be needed anymore. */
+	if (snapshot)
+	{
+		PopActiveSnapshot();
+		UpdateActiveSnapshotCommandId();
+	}
 
-	/* Close relcache entries, but keep lock until transaction commit */
-	table_close(OldHeap, NoLock);
-	if (index)
-		index_close(index, NoLock);
+	if (concurrent)
+	{
+		Assert(!swap_toast_by_content);
 
-	/*
-	 * Close the new relation so it can be dropped as soon as the storage is
-	 * swapped. The relation is not visible to others, so no need to unlock it
-	 * explicitly.
-	 */
-	table_close(NewHeap, NoLock);
+		/*
+		 * Close the index, but keep the lock. Both heaps will be closed by
+		 * the following call.
+		 */
+		if (index)
+			index_close(index, NoLock);
 
-	/*
-	 * Swap the physical files of the target and transient tables, then
-	 * rebuild the target's indexes and throw away the transient table.
-	 */
-	finish_heap_swap(tableOid, OIDNewHeap, is_system_catalog,
-					 swap_toast_by_content, false, true,
-					 frozenXid, cutoffMulti,
-					 relpersistence);
+		rebuild_relation_finish_concurrent(NewHeap, OldHeap, decoding_ctx,
+										   frozenXid, cutoffMulti);
+
+		pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
+									 PROGRESS_REPACK_PHASE_FINAL_CLEANUP);
+
+		/* Done with decoding. */
+		cleanup_logical_decoding(decoding_ctx);
+	}
+	else
+	{
+		bool		is_system_catalog = IsSystemRelation(OldHeap);
+
+		/* Close relcache entries, but keep lock until transaction commit */
+		table_close(OldHeap, NoLock);
+		if (index)
+			index_close(index, NoLock);
+
+		/*
+		 * Close the new relation so it can be dropped as soon as the storage
+		 * is swapped. The relation is not visible to others, so no need to
+		 * unlock it explicitly.
+		 */
+		table_close(NewHeap, NoLock);
+
+		/*
+		 * Swap the physical files of the target and transient tables, then
+		 * rebuild the target's indexes and throw away the transient table.
+		 */
+		finish_heap_swap(tableOid, OIDNewHeap, is_system_catalog,
+						 swap_toast_by_content, false, true, true,
+						 frozenXid, cutoffMulti,
+						 relpersistence);
+	}
 }
 
 
@@ -825,15 +1169,19 @@ make_new_heap(Oid OIDOldHeap, Oid NewTableSpace, Oid NewAccessMethod,
 /*
  * Do the physical copying of table data.
  *
+ * 'snapshot' and 'decoding_ctx': see table_relation_copy_for_cluster(). Pass
+ * iff concurrent processing is required.
+ *
  * There are three output parameters:
  * *pSwapToastByContent is set true if toast tables must be swapped by content.
  * *pFreezeXid receives the TransactionId used as freeze cutoff point.
  * *pCutoffMulti receives the MultiXactId used as a cutoff point.
  */
 static void
-copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verbose,
-				bool *pSwapToastByContent, TransactionId *pFreezeXid,
-				MultiXactId *pCutoffMulti)
+copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex,
+				Snapshot snapshot, LogicalDecodingContext *decoding_ctx,
+				bool verbose, bool *pSwapToastByContent,
+				TransactionId *pFreezeXid, MultiXactId *pCutoffMulti)
 {
 	Relation	relRelation;
 	HeapTuple	reltup;
@@ -850,6 +1198,10 @@ copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verb
 	int			elevel = verbose ? INFO : DEBUG2;
 	PGRUsage	ru0;
 	char	   *nspname;
+	bool		concurrent = snapshot != NULL;
+	LOCKMODE	lmode;
+
+	lmode = concurrent ? ShareUpdateExclusiveLock : AccessExclusiveLock;
 
 	pg_rusage_init(&ru0);
 
@@ -878,7 +1230,7 @@ copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verb
 	 * will be held till end of transaction.
 	 */
 	if (OldHeap->rd_rel->reltoastrelid)
-		LockRelationOid(OldHeap->rd_rel->reltoastrelid, AccessExclusiveLock);
+		LockRelationOid(OldHeap->rd_rel->reltoastrelid, lmode);
 
 	/*
 	 * If both tables have TOAST tables, perform toast swap by content.  It is
@@ -887,7 +1239,8 @@ copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verb
 	 * swap by links.  This is okay because swap by content is only essential
 	 * for system catalogs, and we don't support schema changes for them.
 	 */
-	if (OldHeap->rd_rel->reltoastrelid && NewHeap->rd_rel->reltoastrelid)
+	if (OldHeap->rd_rel->reltoastrelid && NewHeap->rd_rel->reltoastrelid &&
+		!concurrent)
 	{
 		*pSwapToastByContent = true;
 
@@ -908,6 +1261,10 @@ copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verb
 		 * follow the toast pointers to the wrong place.  (It would actually
 		 * work for values copied over from the old toast table, but not for
 		 * any values that we toast which were previously not toasted.)
+		 *
+		 * This would not work with CONCURRENTLY because we may need to delete
+		 * TOASTed tuples from the new heap. With this hack, we'd delete them
+		 * from the old heap.
 		 */
 		NewHeap->rd_toastoid = OldHeap->rd_rel->reltoastrelid;
 	}
@@ -983,7 +1340,9 @@ copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verb
 	 * values (e.g. because the AM doesn't use freezing).
 	 */
 	table_relation_copy_for_cluster(OldHeap, NewHeap, OldIndex, use_sort,
-									cutoffs.OldestXmin, &cutoffs.FreezeLimit,
+									cutoffs.OldestXmin, snapshot,
+									decoding_ctx,
+									&cutoffs.FreezeLimit,
 									&cutoffs.MultiXactCutoff,
 									&num_tuples, &tups_vacuumed,
 									&tups_recently_dead);
@@ -992,7 +1351,11 @@ copy_table_data(Relation NewHeap, Relation OldHeap, Relation OldIndex, bool verb
 	*pFreezeXid = cutoffs.FreezeLimit;
 	*pCutoffMulti = cutoffs.MultiXactCutoff;
 
-	/* Reset rd_toastoid just to be tidy --- it shouldn't be looked at again */
+	/*
+	 * Reset rd_toastoid just to be tidy --- it shouldn't be looked at again.
+	 * In the CONCURRENTLY case, we need to set it again before applying the
+	 * concurrent changes.
+	 */
 	NewHeap->rd_toastoid = InvalidOid;
 
 	num_pages = RelationGetNumberOfBlocks(NewHeap);
@@ -1450,14 +1813,13 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 				 bool swap_toast_by_content,
 				 bool check_constraints,
 				 bool is_internal,
+				 bool reindex,
 				 TransactionId frozenXid,
 				 MultiXactId cutoffMulti,
 				 char newrelpersistence)
 {
 	ObjectAddress object;
 	Oid			mapped_tables[4];
-	int			reindex_flags;
-	ReindexParams reindex_params = {0};
 	int			i;
 
 	/* Report that we are now swapping relation files */
@@ -1483,39 +1845,47 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 	if (is_system_catalog)
 		CacheInvalidateCatalog(OIDOldHeap);
 
-	/*
-	 * Rebuild each index on the relation (but not the toast table, which is
-	 * all-new at this point).  It is important to do this before the DROP
-	 * step because if we are processing a system catalog that will be used
-	 * during DROP, we want to have its indexes available.  There is no
-	 * advantage to the other order anyway because this is all transactional,
-	 * so no chance to reclaim disk space before commit.  We do not need a
-	 * final CommandCounterIncrement() because reindex_relation does it.
-	 *
-	 * Note: because index_build is called via reindex_relation, it will never
-	 * set indcheckxmin true for the indexes.  This is OK even though in some
-	 * sense we are building new indexes rather than rebuilding existing ones,
-	 * because the new heap won't contain any HOT chains at all, let alone
-	 * broken ones, so it can't be necessary to set indcheckxmin.
-	 */
-	reindex_flags = REINDEX_REL_SUPPRESS_INDEX_USE;
-	if (check_constraints)
-		reindex_flags |= REINDEX_REL_CHECK_CONSTRAINTS;
+	if (reindex)
+	{
+		int			reindex_flags;
+		ReindexParams reindex_params = {0};
 
-	/*
-	 * Ensure that the indexes have the same persistence as the parent
-	 * relation.
-	 */
-	if (newrelpersistence == RELPERSISTENCE_UNLOGGED)
-		reindex_flags |= REINDEX_REL_FORCE_INDEXES_UNLOGGED;
-	else if (newrelpersistence == RELPERSISTENCE_PERMANENT)
-		reindex_flags |= REINDEX_REL_FORCE_INDEXES_PERMANENT;
+		/*
+		 * Rebuild each index on the relation (but not the toast table, which
+		 * is all-new at this point).  It is important to do this before the
+		 * DROP step because if we are processing a system catalog that will
+		 * be used during DROP, we want to have its indexes available.  There
+		 * is no advantage to the other order anyway because this is all
+		 * transactional, so no chance to reclaim disk space before commit. We
+		 * do not need a final CommandCounterIncrement() because
+		 * reindex_relation does it.
+		 *
+		 * Note: because index_build is called via reindex_relation, it will
+		 * never set indcheckxmin true for the indexes.  This is OK even
+		 * though in some sense we are building new indexes rather than
+		 * rebuilding existing ones, because the new heap won't contain any
+		 * HOT chains at all, let alone broken ones, so it can't be necessary
+		 * to set indcheckxmin.
+		 */
+		reindex_flags = REINDEX_REL_SUPPRESS_INDEX_USE;
+		if (check_constraints)
+			reindex_flags |= REINDEX_REL_CHECK_CONSTRAINTS;
 
-	/* Report that we are now reindexing relations */
-	pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
-								 PROGRESS_REPACK_PHASE_REBUILD_INDEX);
+		/*
+		 * Ensure that the indexes have the same persistence as the parent
+		 * relation.
+		 */
+		if (newrelpersistence == RELPERSISTENCE_UNLOGGED)
+			reindex_flags |= REINDEX_REL_FORCE_INDEXES_UNLOGGED;
+		else if (newrelpersistence == RELPERSISTENCE_PERMANENT)
+			reindex_flags |= REINDEX_REL_FORCE_INDEXES_PERMANENT;
 
-	reindex_relation(NULL, OIDOldHeap, reindex_flags, &reindex_params);
+		/* Report that we are now reindexing relations */
+		pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
+									 PROGRESS_REPACK_PHASE_REBUILD_INDEX);
+
+		reindex_relation(NULL, OIDOldHeap, reindex_flags, &reindex_params);
+	}
 
 	/* Report that we are now doing clean up */
 	pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
@@ -1559,6 +1929,17 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 	object.objectId = OIDNewHeap;
 	object.objectSubId = 0;
 
+	if (!reindex)
+	{
+		/*
+		 * Make sure the changes in pg_class are visible. This is especially
+		 * important if !swap_toast_by_content, so that the correct TOAST
+		 * relation is dropped. (reindex_relation() above did not help in this
+		 * case))
+		 */
+		CommandCounterIncrement();
+	}
+
 	/*
 	 * The new relation is local to our transaction and we know nothing
 	 * depends on it, so DROP_RESTRICT should be OK.
@@ -1598,7 +1979,7 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 
 			/* Get the associated valid index to be renamed */
 			toastidx = toast_get_valid_index(newrel->rd_rel->reltoastrelid,
-											 NoLock);
+											 AccessExclusiveLock);
 
 			/* rename the toast table ... */
 			snprintf(NewToastName, NAMEDATALEN, "pg_toast_%u",
@@ -1858,7 +2239,8 @@ cluster_is_permitted_for_relation(RepackCommand cmd, Oid relid, Oid userid)
  * case, if an index name is given, it's up to the caller to resolve it.
  */
 static Relation
-process_single_relation(RepackStmt *stmt, ClusterParams *params)
+process_single_relation(RepackStmt *stmt, LOCKMODE lockmode, bool isTopLevel,
+						ClusterParams *params)
 {
 	Relation	rel;
 	Oid			tableOid;
@@ -1867,13 +2249,9 @@ process_single_relation(RepackStmt *stmt, ClusterParams *params)
 	Assert(stmt->command == REPACK_COMMAND_CLUSTER ||
 		   stmt->command == REPACK_COMMAND_REPACK);
 
-	/*
-	 * Find, lock, and check permissions on the table.  We obtain
-	 * AccessExclusiveLock right away to avoid lock-upgrade hazard in the
-	 * single-transaction case.
-	 */
+	/* Find, lock, and check permissions on the table. */
 	tableOid = RangeVarGetRelidExtended(stmt->relation->relation,
-										AccessExclusiveLock,
+										lockmode,
 										0,
 										RangeVarCallbackMaintainsTable,
 										NULL);
@@ -1905,13 +2283,14 @@ process_single_relation(RepackStmt *stmt, ClusterParams *params)
 		return rel;
 	else
 	{
-		Oid			indexOid;
+		Oid			indexOid = InvalidOid;
 
 		indexOid = determine_clustered_index(rel, stmt->usingindex,
 											 stmt->indexname);
 		if (OidIsValid(indexOid))
-			check_index_is_clusterable(rel, indexOid, AccessExclusiveLock);
-		cluster_rel(stmt->command, rel, indexOid, params);
+			check_index_is_clusterable(rel, indexOid, lockmode);
+
+		cluster_rel(stmt->command, rel, indexOid, params, isTopLevel);
 
 		/* Do an analyze, if requested */
 		if (params->options & CLUOPT_ANALYZE)
@@ -1994,3 +2373,1047 @@ RepackCommandAsString(RepackCommand cmd)
 	}
 	return "???";	/* keep compiler quiet */
 }
+
+
+/*
+ * Call this function before REPACK CONCURRENTLY starts to setup logical
+ * decoding. It makes sure that other users of the table put enough
+ * information into WAL.
+ *
+ * The point is that at various places we expect that the table we're
+ * processing is treated like a system catalog. For example, we need to be
+ * able to scan it using a "historic snapshot" anytime during the processing
+ * (as opposed to scanning only at the start point of the decoding, as logical
+ * replication does during initial table synchronization), in order to apply
+ * concurrent UPDATE / DELETE commands.
+ *
+ * Note that TOAST table needs no attention here as it's not scanned using
+ * historic snapshot.
+ */
+static void
+begin_concurrent_repack(Relation rel)
+{
+	Oid			toastrelid;
+
+	/*
+	 * Avoid logical decoding of other relations by this backend. The lock we
+	 * have guarantees that the actual locator cannot be changed concurrently:
+	 * TRUNCATE needs AccessExclusiveLock.
+	 */
+	Assert(CheckRelationLockedByMe(rel, ShareUpdateExclusiveLock, false));
+	repacked_rel_locator = rel->rd_locator;
+	toastrelid = rel->rd_rel->reltoastrelid;
+	if (OidIsValid(toastrelid))
+	{
+		Relation	toastrel;
+
+		/* Avoid logical decoding of other TOAST relations. */
+		toastrel = table_open(toastrelid, AccessShareLock);
+		repacked_rel_toast_locator = toastrel->rd_locator;
+		table_close(toastrel, AccessShareLock);
+	}
+}
+
+/*
+ * Call this when done with REPACK CONCURRENTLY.
+ */
+static void
+end_concurrent_repack(void)
+{
+	/*
+	 * Restore normal function of (future) logical decoding for this backend.
+	 */
+	repacked_rel_locator.relNumber = InvalidOid;
+	repacked_rel_toast_locator.relNumber = InvalidOid;
+}
+
+/*
+ * Is this backend performing logical decoding on behalf of REPACK
+ * (CONCURRENTLY) ?
+ */
+bool
+am_decoding_for_repack(void)
+{
+	return OidIsValid(repacked_rel_locator.relNumber);
+}
+
+/*
+ * Does the WAL record contain a data change that this backend does not need
+ * to decode on behalf of REPACK (CONCURRENTLY)?
+ */
+bool
+change_useless_for_repack(XLogRecordBuffer *buf)
+{
+	XLogReaderState *r = buf->record;
+	RelFileLocator locator;
+
+	/* TOAST locator should not be set unless the main is. */
+	Assert(!OidIsValid(repacked_rel_toast_locator.relNumber) ||
+		   OidIsValid(repacked_rel_locator.relNumber));
+
+	/*
+	 * Backends not involved in REPACK (CONCURRENTLY) should not do the
+	 * filtering.
+	 */
+	if (!am_decoding_for_repack())
+		return false;
+
+	/*
+	 * If the record does not contain the block 0, it's probably not INSERT /
+	 * UPDATE / DELETE. In any case, we do not have enough information to
+	 * filter the change out.
+	 */
+	if (!XLogRecGetBlockTagExtended(r, 0, &locator, NULL, NULL, NULL))
+		return false;
+
+	/*
+	 * Decode the change if it belongs to the table we are repacking, or if it
+	 * belongs to its TOAST relation.
+	 */
+	if (RelFileLocatorEquals(locator, repacked_rel_locator))
+		return false;
+	if (OidIsValid(repacked_rel_toast_locator.relNumber) &&
+		RelFileLocatorEquals(locator, repacked_rel_toast_locator))
+		return false;
+
+	/* Filter out changes of other tables. */
+	return true;
+}
+
+/*
+ * This function is much like pg_create_logical_replication_slot() except that
+ * the new slot is neither released (if anyone else could read changes from
+ * our slot, we could miss changes other backends do while we copy the
+ * existing data into temporary table), nor persisted (it's easier to handle
+ * crash by restarting all the work from scratch).
+ */
+static LogicalDecodingContext *
+setup_logical_decoding(Oid relid)
+{
+	Relation	rel;
+	TupleDesc	tupdesc;
+	LogicalDecodingContext *ctx;
+	RepackDecodingState *dstate = palloc0_object(RepackDecodingState);
+
+	/*
+	 * REPACK CONCURRENTLY is not allowed in a transaction block, so this
+	 * should never fire.
+	 */
+	Assert(!TransactionIdIsValid(GetTopTransactionIdIfAny()));
+
+	/*
+	 * A single backend should not execute multiple REPACK commands at a time,
+	 * so use PID to make the slot unique.
+	 */
+	snprintf(NameStr(dstate->slotname), NAMEDATALEN, "repack_%d", MyProcPid);
+
+	/*
+	 * Make sure we can use logical decoding.
+	 */
+	CheckSlotPermissions();
+	CheckLogicalDecodingRequirements();
+	/* RS_TEMPORARY so that the slot gets cleaned up on ERROR. */
+	ReplicationSlotCreate(NameStr(dstate->slotname), true, RS_TEMPORARY,
+						  false, false, false);
+	EnsureLogicalDecodingEnabled();
+
+	/*
+	 * Neither prepare_write nor do_write callback nor update_progress is
+	 * useful for us.
+	 */
+	ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME,
+									NIL,
+									true,
+									InvalidXLogRecPtr,
+									XL_ROUTINE(.page_read = read_local_xlog_page,
+											   .segment_open = wal_segment_open,
+											   .segment_close = wal_segment_close),
+									NULL, NULL, NULL);
+
+	/*
+	 * We don't have control on setting fast_forward, so at least check it.
+	 */
+	Assert(!ctx->fast_forward);
+
+	DecodingContextFindStartpoint(ctx);
+
+	/* Some WAL records should have been read. */
+	Assert(ctx->reader->EndRecPtr != InvalidXLogRecPtr);
+
+	XLByteToSeg(ctx->reader->EndRecPtr, repack_current_segment,
+				wal_segment_size);
+
+	/*
+	 * Setup structures to store decoded changes.
+	 */
+	dstate->relid = relid;
+	dstate->tstore = tuplestore_begin_heap(false, false,
+										   maintenance_work_mem);
+
+	/* Caller should already have the table locked. */
+	rel = table_open(relid, NoLock);
+	tupdesc = CreateTupleDescCopy(RelationGetDescr(rel));
+	dstate->tupdesc = tupdesc;
+	table_close(rel, NoLock);
+
+	/* Initialize the descriptor to store the changes ... */
+	dstate->tupdesc_change = CreateTemplateTupleDesc(1);
+
+	TupleDescInitEntry(dstate->tupdesc_change, 1, NULL, BYTEAOID, -1, 0);
+	/* ... as well as the corresponding slot. */
+	dstate->tsslot = MakeSingleTupleTableSlot(dstate->tupdesc_change,
+											  &TTSOpsMinimalTuple);
+
+	dstate->resowner = ResourceOwnerCreate(CurrentResourceOwner,
+										   "logical decoding");
+
+	ctx->output_writer_private = dstate;
+	return ctx;
+}
+
+/*
+ * Retrieve tuple from ConcurrentChange structure.
+ *
+ * The input data starts with the structure but it might not be appropriately
+ * aligned.
+ */
+static HeapTuple
+get_changed_tuple(char *change)
+{
+	HeapTupleData tup_data;
+	HeapTuple	result;
+	char	   *src;
+
+	/*
+	 * Ensure alignment before accessing the fields. (This is why we can't use
+	 * heap_copytuple() instead of this function.)
+	 */
+	src = change + offsetof(ConcurrentChange, tup_data);
+	memcpy(&tup_data, src, sizeof(HeapTupleData));
+
+	result = (HeapTuple) palloc(HEAPTUPLESIZE + tup_data.t_len);
+	memcpy(result, &tup_data, sizeof(HeapTupleData));
+	result->t_data = (HeapTupleHeader) ((char *) result + HEAPTUPLESIZE);
+	src = change + SizeOfConcurrentChange;
+	memcpy(result->t_data, src, result->t_len);
+
+	return result;
+}
+
+/*
+ * Decode logical changes from the WAL sequence up to end_of_wal.
+ */
+void
+repack_decode_concurrent_changes(LogicalDecodingContext *ctx,
+								 XLogRecPtr end_of_wal)
+{
+	RepackDecodingState *dstate;
+	ResourceOwner resowner_old;
+
+	dstate = (RepackDecodingState *) ctx->output_writer_private;
+	resowner_old = CurrentResourceOwner;
+	CurrentResourceOwner = dstate->resowner;
+
+	PG_TRY();
+	{
+		while (ctx->reader->EndRecPtr < end_of_wal)
+		{
+			XLogRecord *record;
+			XLogSegNo	segno_new;
+			char	   *errm = NULL;
+			XLogRecPtr	end_lsn;
+
+			record = XLogReadRecord(ctx->reader, &errm);
+			if (errm)
+				elog(ERROR, "%s", errm);
+
+			if (record != NULL)
+				LogicalDecodingProcessRecord(ctx, ctx->reader);
+
+			/*
+			 * If WAL segment boundary has been crossed, inform the decoding
+			 * system that the catalog_xmin can advance. (We can confirm more
+			 * often, but a filling a single WAL segment should not take much
+			 * time.)
+			 */
+			end_lsn = ctx->reader->EndRecPtr;
+			XLByteToSeg(end_lsn, segno_new, wal_segment_size);
+			if (segno_new != repack_current_segment)
+			{
+				LogicalConfirmReceivedLocation(end_lsn);
+				elog(DEBUG1, "REPACK: confirmed receive location %X/%X",
+					 (uint32) (end_lsn >> 32), (uint32) end_lsn);
+				repack_current_segment = segno_new;
+			}
+
+			CHECK_FOR_INTERRUPTS();
+		}
+		InvalidateSystemCaches();
+		CurrentResourceOwner = resowner_old;
+	}
+	PG_CATCH();
+	{
+		/* clear all timetravel entries */
+		InvalidateSystemCaches();
+		CurrentResourceOwner = resowner_old;
+		PG_RE_THROW();
+	}
+	PG_END_TRY();
+}
+
+/*
+ * Apply changes stored in 'file'.
+ */
+static void
+apply_concurrent_changes(RepackDecodingState *dstate, ChangeDest *dest)
+{
+	Relation	rel = dest->rel;
+	TupleTableSlot *index_slot,
+			   *ident_slot;
+	HeapTuple	tup_old = NULL;
+
+	if (dstate->nchanges == 0)
+		return;
+
+	/* TupleTableSlot is needed to pass the tuple to ExecInsertIndexTuples(). */
+	index_slot = MakeSingleTupleTableSlot(dstate->tupdesc, &TTSOpsHeapTuple);
+
+	/* A slot to fetch tuples from identity index. */
+	ident_slot = table_slot_create(rel, NULL);
+
+	while (tuplestore_gettupleslot(dstate->tstore, true, false,
+								   dstate->tsslot))
+	{
+		bool		shouldFree;
+		HeapTuple	tup_change,
+					tup,
+					tup_exist;
+		char	   *change_raw,
+				   *src;
+		ConcurrentChange change;
+		bool		isnull[1];
+		Datum		values[1];
+
+		CHECK_FOR_INTERRUPTS();
+
+		/* Get the change from the single-column tuple. */
+		tup_change = ExecFetchSlotHeapTuple(dstate->tsslot, false, &shouldFree);
+		heap_deform_tuple(tup_change, dstate->tupdesc_change, values, isnull);
+		Assert(!isnull[0]);
+
+		/* Make sure we access aligned data. */
+		change_raw = (char *) DatumGetByteaP(values[0]);
+		src = (char *) VARDATA(change_raw);
+		memcpy(&change, src, SizeOfConcurrentChange);
+
+		/*
+		 * Extract the tuple from the change. The tuple is copied here because
+		 * it might be assigned to 'tup_old', in which case it needs to
+		 * survive into the next iteration.
+		 */
+		tup = get_changed_tuple(src);
+
+		if (change.kind == CHANGE_UPDATE_OLD)
+		{
+			Assert(tup_old == NULL);
+			tup_old = tup;
+		}
+		else if (change.kind == CHANGE_INSERT)
+		{
+			Assert(tup_old == NULL);
+
+			apply_concurrent_insert(rel, tup, dest->iistate, index_slot);
+
+			pfree(tup);
+		}
+		else if (change.kind == CHANGE_UPDATE_NEW ||
+				 change.kind == CHANGE_DELETE)
+		{
+			HeapTuple	tup_key;
+
+			if (change.kind == CHANGE_UPDATE_NEW)
+			{
+				tup_key = tup_old != NULL ? tup_old : tup;
+			}
+			else
+			{
+				Assert(tup_old == NULL);
+				tup_key = tup;
+			}
+
+			/*
+			 * Find the tuple to be updated or deleted.
+			 */
+			tup_exist = find_target_tuple(rel, dest, tup_key, ident_slot);
+			if (tup_exist == NULL)
+				elog(ERROR, "failed to find target tuple");
+
+			if (change.kind == CHANGE_UPDATE_NEW)
+				apply_concurrent_update(rel, tup, tup_exist, dest->iistate,
+										index_slot);
+			else
+				apply_concurrent_delete(rel, tup_exist);
+
+			if (tup_old != NULL)
+			{
+				pfree(tup_old);
+				tup_old = NULL;
+			}
+
+			pfree(tup);
+		}
+		else
+			elog(ERROR, "unrecognized kind of change: %d", change.kind);
+
+		/*
+		 * If a change was applied now, increment CID for next writes and
+		 * update the snapshot so it sees the changes we've applied so far.
+		 */
+		if (change.kind != CHANGE_UPDATE_OLD)
+		{
+			CommandCounterIncrement();
+			UpdateActiveSnapshotCommandId();
+		}
+
+		/* TTSOpsMinimalTuple has .get_heap_tuple==NULL. */
+		Assert(shouldFree);
+		pfree(tup_change);
+	}
+
+	tuplestore_clear(dstate->tstore);
+	dstate->nchanges = 0;
+
+	/* Cleanup. */
+	ExecDropSingleTupleTableSlot(index_slot);
+	ExecDropSingleTupleTableSlot(ident_slot);
+}
+
+static void
+apply_concurrent_insert(Relation rel, HeapTuple tup, IndexInsertState *iistate,
+						TupleTableSlot *index_slot)
+{
+	List	   *recheck;
+
+	/*
+	 * Like simple_heap_insert(), but make sure that the INSERT is not
+	 * logically decoded - see reform_and_rewrite_tuple() for more
+	 * information.
+	 */
+	heap_insert(rel, tup, GetCurrentCommandId(true), HEAP_INSERT_NO_LOGICAL,
+				NULL);
+
+	/*
+	 * Update indexes.
+	 *
+	 * In case functions in the index need the active snapshot and caller
+	 * hasn't set one.
+	 */
+	ExecStoreHeapTuple(tup, index_slot, false);
+	recheck = ExecInsertIndexTuples(iistate->rri,
+									index_slot,
+									iistate->estate,
+									false,	/* update */
+									false,	/* noDupErr */
+									NULL,	/* specConflict */
+									NIL,	/* arbiterIndexes */
+									false	/* onlySummarizing */
+		);
+
+	/*
+	 * If recheck is required, it must have been performed on the source
+	 * relation by now. (All the logical changes we process here are already
+	 * committed.)
+	 */
+	list_free(recheck);
+
+	pgstat_progress_incr_param(PROGRESS_REPACK_HEAP_TUPLES_INSERTED, 1);
+}
+
+static void
+apply_concurrent_update(Relation rel, HeapTuple tup, HeapTuple tup_target,
+						IndexInsertState *iistate, TupleTableSlot *index_slot)
+{
+	LockTupleMode lockmode;
+	TM_FailureData tmfd;
+	TU_UpdateIndexes update_indexes;
+	TM_Result	res;
+	List	   *recheck;
+
+	/*
+	 * Write the new tuple into the new heap. ('tup' gets the TID assigned
+	 * here.)
+	 *
+	 * Do it like in simple_heap_update(), except for 'wal_logical' (and
+	 * except for 'wait').
+	 */
+	res = heap_update(rel, &tup_target->t_self, tup,
+					  GetCurrentCommandId(true),
+					  InvalidSnapshot,
+					  false,	/* no wait - only we are doing changes */
+					  &tmfd, &lockmode, &update_indexes,
+					  false /* wal_logical */ );
+	if (res != TM_Ok)
+		ereport(ERROR, (errmsg("failed to apply concurrent UPDATE")));
+
+	ExecStoreHeapTuple(tup, index_slot, false);
+
+	if (update_indexes != TU_None)
+	{
+		recheck = ExecInsertIndexTuples(iistate->rri,
+										index_slot,
+										iistate->estate,
+										true,	/* update */
+										false,	/* noDupErr */
+										NULL,	/* specConflict */
+										NIL,	/* arbiterIndexes */
+		/* onlySummarizing */
+										update_indexes == TU_Summarizing);
+		list_free(recheck);
+	}
+
+	pgstat_progress_incr_param(PROGRESS_REPACK_HEAP_TUPLES_UPDATED, 1);
+}
+
+static void
+apply_concurrent_delete(Relation rel, HeapTuple tup_target)
+{
+	TM_Result	res;
+	TM_FailureData tmfd;
+
+	/*
+	 * Delete tuple from the new heap.
+	 *
+	 * Do it like in simple_heap_delete(), except for 'wal_logical' (and
+	 * except for 'wait').
+	 */
+	res = heap_delete(rel, &tup_target->t_self, GetCurrentCommandId(true),
+					  InvalidSnapshot, false,
+					  &tmfd,
+					  false,	/* no wait - only we are doing changes */
+					  false /* wal_logical */ );
+
+	if (res != TM_Ok)
+		ereport(ERROR, (errmsg("failed to apply concurrent DELETE")));
+
+	pgstat_progress_incr_param(PROGRESS_REPACK_HEAP_TUPLES_DELETED, 1);
+}
+
+/*
+ * Find the tuple to be updated or deleted.
+ *
+ * 'tup_key' is a tuple containing the key values for the scan.
+ */
+static HeapTuple
+find_target_tuple(Relation rel, ChangeDest *dest, HeapTuple tup_key,
+				  TupleTableSlot *ident_slot)
+{
+	Relation	ident_index = dest->ident_index;
+	IndexScanDesc scan;
+	Form_pg_index ident_form;
+	int2vector *ident_indkey;
+	HeapTuple	result = NULL;
+
+	/* XXX no instrumentation for now */
+	scan = index_beginscan(rel, ident_index, GetActiveSnapshot(),
+						   NULL, dest->ident_key_nentries, 0);
+
+	/*
+	 * Scan key is passed by caller, so it does not have to be constructed
+	 * multiple times. Key entries have all fields initialized, except for
+	 * sk_argument.
+	 */
+	index_rescan(scan, dest->ident_key, dest->ident_key_nentries, NULL, 0);
+
+	/* Info needed to retrieve key values from heap tuple. */
+	ident_form = ident_index->rd_index;
+	ident_indkey = &ident_form->indkey;
+
+	/* Use the incoming tuple to finalize the scan key. */
+	for (int i = 0; i < scan->numberOfKeys; i++)
+	{
+		ScanKey		entry;
+		bool		isnull;
+		int16		attno_heap;
+
+		entry = &scan->keyData[i];
+		attno_heap = ident_indkey->values[i];
+		entry->sk_argument = heap_getattr(tup_key,
+										  attno_heap,
+										  rel->rd_att,
+										  &isnull);
+		Assert(!isnull);
+	}
+	if (index_getnext_slot(scan, ForwardScanDirection, ident_slot))
+	{
+		bool		shouldFree;
+
+		result = ExecFetchSlotHeapTuple(ident_slot, false, &shouldFree);
+		/* TTSOpsBufferHeapTuple has .get_heap_tuple != NULL. */
+		Assert(!shouldFree);
+	}
+	index_endscan(scan);
+
+	return result;
+}
+
+/*
+ * Decode and apply concurrent changes.
+ */
+static void
+process_concurrent_changes(LogicalDecodingContext *decoding_ctx,
+						   XLogRecPtr end_of_wal, ChangeDest *dest)
+{
+	RepackDecodingState *dstate;
+
+	pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
+								 PROGRESS_REPACK_PHASE_CATCH_UP);
+
+	dstate = (RepackDecodingState *) decoding_ctx->output_writer_private;
+
+	repack_decode_concurrent_changes(decoding_ctx, end_of_wal);
+
+	if (dstate->nchanges == 0)
+		return;
+
+	apply_concurrent_changes(dstate, dest);
+}
+
+/*
+ * Initialize IndexInsertState for index specified by ident_index_id.
+ *
+ * While doing that, also return the identity index in *ident_index_p.
+ */
+static IndexInsertState *
+get_index_insert_state(Relation relation, Oid ident_index_id,
+					   Relation *ident_index_p)
+{
+	EState	   *estate;
+	int			i;
+	IndexInsertState *result;
+	Relation	ident_index = NULL;
+
+	result = (IndexInsertState *) palloc0(sizeof(IndexInsertState));
+	estate = CreateExecutorState();
+
+	result->rri = (ResultRelInfo *) palloc(sizeof(ResultRelInfo));
+	InitResultRelInfo(result->rri, relation, 0, 0, 0);
+	ExecOpenIndices(result->rri, false);
+
+	/*
+	 * Find the relcache entry of the identity index so that we spend no extra
+	 * effort to open / close it.
+	 */
+	for (i = 0; i < result->rri->ri_NumIndices; i++)
+	{
+		Relation	ind_rel;
+
+		ind_rel = result->rri->ri_IndexRelationDescs[i];
+		if (ind_rel->rd_id == ident_index_id)
+			ident_index = ind_rel;
+	}
+	if (ident_index == NULL)
+		elog(ERROR, "failed to open identity index");
+
+	/* Only initialize fields needed by ExecInsertIndexTuples(). */
+	result->estate = estate;
+
+	*ident_index_p = ident_index;
+	return result;
+}
+
+/*
+ * Build scan key to process logical changes.
+ */
+static ScanKey
+build_identity_key(Oid ident_idx_oid, Relation rel_src, int *nentries)
+{
+	Relation	ident_idx_rel;
+	Form_pg_index ident_idx;
+	int			n,
+				i;
+	ScanKey		result;
+
+	Assert(OidIsValid(ident_idx_oid));
+	ident_idx_rel = index_open(ident_idx_oid, AccessShareLock);
+	ident_idx = ident_idx_rel->rd_index;
+	n = ident_idx->indnatts;
+	result = (ScanKey) palloc(sizeof(ScanKeyData) * n);
+	for (i = 0; i < n; i++)
+	{
+		ScanKey		entry;
+		int16		relattno;
+		Form_pg_attribute att;
+		Oid			opfamily,
+					opcintype,
+					opno,
+					opcode;
+
+		entry = &result[i];
+		relattno = ident_idx->indkey.values[i];
+		if (relattno >= 1)
+		{
+			TupleDesc	desc;
+
+			desc = rel_src->rd_att;
+			att = TupleDescAttr(desc, relattno - 1);
+		}
+		else
+			elog(ERROR, "unexpected attribute number %d in index", relattno);
+
+		opfamily = ident_idx_rel->rd_opfamily[i];
+		opcintype = ident_idx_rel->rd_opcintype[i];
+		opno = get_opfamily_member(opfamily, opcintype, opcintype,
+								   BTEqualStrategyNumber);
+
+		if (!OidIsValid(opno))
+			elog(ERROR, "failed to find = operator for type %u", opcintype);
+
+		opcode = get_opcode(opno);
+		if (!OidIsValid(opcode))
+			elog(ERROR, "failed to find = operator for operator %u", opno);
+
+		/* Initialize everything but argument. */
+		ScanKeyInit(entry,
+					i + 1,
+					BTEqualStrategyNumber, opcode,
+					(Datum) NULL);
+		entry->sk_collation = att->attcollation;
+	}
+	index_close(ident_idx_rel, AccessShareLock);
+
+	*nentries = n;
+	return result;
+}
+
+static void
+free_index_insert_state(IndexInsertState *iistate)
+{
+	ExecCloseIndices(iistate->rri);
+	FreeExecutorState(iistate->estate);
+	pfree(iistate->rri);
+	pfree(iistate);
+}
+
+static void
+cleanup_logical_decoding(LogicalDecodingContext *ctx)
+{
+	RepackDecodingState *dstate;
+
+	dstate = (RepackDecodingState *) ctx->output_writer_private;
+
+	ExecDropSingleTupleTableSlot(dstate->tsslot);
+	FreeTupleDesc(dstate->tupdesc_change);
+	FreeTupleDesc(dstate->tupdesc);
+	tuplestore_end(dstate->tstore);
+
+	FreeDecodingContext(ctx);
+
+	ReplicationSlotRelease();
+	ReplicationSlotDrop(NameStr(dstate->slotname), false);
+	pfree(dstate);
+}
+
+/*
+ * The final steps of rebuild_relation() for concurrent processing.
+ *
+ * On entry, NewHeap is locked in AccessExclusiveLock mode. OldHeap and its
+ * clustering index (if one is passed) are still locked in a mode that allows
+ * concurrent data changes. On exit, both tables and their indexes are closed,
+ * but locked in AccessExclusiveLock mode.
+ */
+static void
+rebuild_relation_finish_concurrent(Relation NewHeap, Relation OldHeap,
+								   LogicalDecodingContext *decoding_ctx,
+								   TransactionId frozenXid,
+								   MultiXactId cutoffMulti)
+{
+	LOCKMODE	lockmode_old PG_USED_FOR_ASSERTS_ONLY;
+	List	   *ind_oids_new;
+	Oid			old_table_oid = RelationGetRelid(OldHeap);
+	Oid			new_table_oid = RelationGetRelid(NewHeap);
+	List	   *ind_oids_old = RelationGetIndexList(OldHeap);
+	ListCell   *lc,
+			   *lc2;
+	char		relpersistence;
+	bool		is_system_catalog;
+	Oid			ident_idx_old,
+				ident_idx_new;
+	XLogRecPtr	wal_insert_ptr,
+				end_of_wal;
+	char		dummy_rec_data = '\0';
+	Relation   *ind_refs,
+			   *ind_refs_p;
+	int			nind;
+	ChangeDest	chgdst;
+
+	/* Like in cluster_rel(). */
+	lockmode_old = ShareUpdateExclusiveLock;
+	Assert(CheckRelationLockedByMe(OldHeap, lockmode_old, false));
+	/* This is expected from the caller. */
+	Assert(CheckRelationLockedByMe(NewHeap, AccessExclusiveLock, false));
+
+	ident_idx_old = RelationGetReplicaIndex(OldHeap);
+
+	/*
+	 * Unlike the exclusive case, we build new indexes for the new relation
+	 * rather than swapping the storage and reindexing the old relation. The
+	 * point is that the index build can take some time, so we do it before we
+	 * get AccessExclusiveLock on the old heap and therefore we cannot swap
+	 * the heap storage yet.
+	 *
+	 * index_create() will lock the new indexes using AccessExclusiveLock - no
+	 * need to change that. At the same time, we use ShareUpdateExclusiveLock
+	 * to lock the existing indexes - that should be enough to prevent others
+	 * from changing them while we're repacking the relation. The lock on
+	 * table should prevent others from changing the index column list, but
+	 * might not be enough for commands like ALTER INDEX ... SET ... (Those
+	 * are not necessarily dangerous, but can make user confused if the
+	 * changes they do get lost due to REPACK.)
+	 */
+	ind_oids_new = build_new_indexes(NewHeap, OldHeap, ind_oids_old);
+
+	/*
+	 * Processing shouldn't start w/o valid identity index.
+	 */
+	Assert(OidIsValid(ident_idx_old));
+
+	/* Find "identity index" on the new relation. */
+	ident_idx_new = InvalidOid;
+	forboth(lc, ind_oids_old, lc2, ind_oids_new)
+	{
+		Oid			ind_old = lfirst_oid(lc);
+		Oid			ind_new = lfirst_oid(lc2);
+
+		if (ident_idx_old == ind_old)
+		{
+			ident_idx_new = ind_new;
+			break;
+		}
+	}
+	if (!OidIsValid(ident_idx_new))
+
+		/*
+		 * Should not happen, given our lock on the old relation.
+		 */
+		ereport(ERROR,
+				(errmsg("identity index missing on the new relation")));
+
+	/* Gather information to apply concurrent changes. */
+	chgdst.rel = NewHeap;
+	chgdst.iistate = get_index_insert_state(NewHeap, ident_idx_new,
+											&chgdst.ident_index);
+	chgdst.ident_key = build_identity_key(ident_idx_new, OldHeap,
+										  &chgdst.ident_key_nentries);
+
+	/*
+	 * During testing, wait for another backend to perform concurrent data
+	 * changes which we will process below.
+	 */
+	INJECTION_POINT("repack-concurrently-before-lock", NULL);
+
+	/*
+	 * Flush all WAL records inserted so far (possibly except for the last
+	 * incomplete page, see GetInsertRecPtr), to minimize the amount of data
+	 * we need to flush while holding exclusive lock on the source table.
+	 */
+	wal_insert_ptr = GetInsertRecPtr();
+	XLogFlush(wal_insert_ptr);
+	end_of_wal = GetFlushRecPtr(NULL);
+
+	/*
+	 * Apply concurrent changes first time, to minimize the time we need to
+	 * hold AccessExclusiveLock. (Quite some amount of WAL could have been
+	 * written during the data copying and index creation.)
+	 */
+	process_concurrent_changes(decoding_ctx, end_of_wal, &chgdst);
+
+	/*
+	 * Acquire AccessExclusiveLock on the table, its TOAST relation (if there
+	 * is one), all its indexes, so that we can swap the files.
+	 */
+	LockRelationOid(old_table_oid, AccessExclusiveLock);
+
+	/*
+	 * Lock all indexes now, not only the clustering one: all indexes need to
+	 * have their files swapped. While doing that, store their relation
+	 * references in an array, to handle predicate locks below.
+	 */
+	ind_refs_p = ind_refs = palloc_array(Relation, list_length(ind_oids_old));
+	nind = 0;
+	foreach_oid(ind_oid, ind_oids_old)
+	{
+		Relation	index;
+
+		index = index_open(ind_oid, AccessExclusiveLock);
+
+		/*
+		 * TODO 1) Do we need to check if ALTER INDEX was executed since the
+		 * new index was created in build_new_indexes()? 2) Specifically for
+		 * the clustering index, should check_index_is_clusterable() be called
+		 * here? (Not sure about the latter: ShareUpdateExclusiveLock on the
+		 * table probably blocks all commands that affect the result of
+		 * check_index_is_clusterable().)
+		 */
+		*ind_refs_p = index;
+		ind_refs_p++;
+		nind++;
+	}
+
+	/*
+	 * Lock the OldHeap's TOAST relation exclusively - again, the lock is
+	 * needed to swap the files.
+	 */
+	if (OidIsValid(OldHeap->rd_rel->reltoastrelid))
+		LockRelationOid(OldHeap->rd_rel->reltoastrelid, AccessExclusiveLock);
+
+	/*
+	 * Tuples and pages of the old heap will be gone, but the heap will stay.
+	 */
+	TransferPredicateLocksToHeapRelation(OldHeap);
+	/* The same for indexes. */
+	for (int i = 0; i < nind; i++)
+	{
+		Relation	index = ind_refs[i];
+
+		TransferPredicateLocksToHeapRelation(index);
+
+		/*
+		 * References to indexes on the old relation are not needed anymore,
+		 * however locks stay till the end of the transaction.
+		 */
+		index_close(index, NoLock);
+	}
+	pfree(ind_refs);
+
+	/*
+	 * Flush anything we see in WAL, to make sure that all changes committed
+	 * while we were waiting for the exclusive lock are available for
+	 * decoding. This should not be necessary if all backends had
+	 * synchronous_commit set, but we can't rely on this setting.
+	 *
+	 * Unfortunately, GetInsertRecPtr() may lag behind the actual insert
+	 * position, and GetLastImportantRecPtr() points at the start of the last
+	 * record rather than at the end. Thus the simplest way to determine the
+	 * insert position is to insert a dummy record and use its LSN.
+	 *
+	 * XXX Consider using GetLastImportantRecPtr() and adding the size of the
+	 * last record (plus the total size of all the page headers the record
+	 * spans)?
+	 */
+	XLogBeginInsert();
+	XLogRegisterData(&dummy_rec_data, 1);
+	wal_insert_ptr = XLogInsert(RM_XLOG_ID, XLOG_NOOP);
+	XLogFlush(wal_insert_ptr);
+	end_of_wal = GetFlushRecPtr(NULL);
+
+	/* Apply the concurrent changes again. */
+	process_concurrent_changes(decoding_ctx, end_of_wal, &chgdst);
+
+	/* Remember info about rel before closing OldHeap */
+	relpersistence = OldHeap->rd_rel->relpersistence;
+	is_system_catalog = IsSystemRelation(OldHeap);
+
+	pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
+								 PROGRESS_REPACK_PHASE_SWAP_REL_FILES);
+
+	/*
+	 * Even ShareUpdateExclusiveLock should have prevented others from
+	 * creating / dropping indexes (even using the CONCURRENTLY option), so we
+	 * do not need to check whether the lists match.
+	 */
+	forboth(lc, ind_oids_old, lc2, ind_oids_new)
+	{
+		Oid			ind_old = lfirst_oid(lc);
+		Oid			ind_new = lfirst_oid(lc2);
+		Oid			mapped_tables[4];
+
+		/* Zero out possible results from swapped_relation_files */
+		memset(mapped_tables, 0, sizeof(mapped_tables));
+
+		swap_relation_files(ind_old, ind_new,
+							(old_table_oid == RelationRelationId),
+							false,	/* swap_toast_by_content */
+							true,
+							InvalidTransactionId,
+							InvalidMultiXactId,
+							mapped_tables);
+
+#ifdef USE_ASSERT_CHECKING
+
+		/*
+		 * Concurrent processing is not supported for system relations, so
+		 * there should be no mapped tables.
+		 */
+		for (int i = 0; i < 4; i++)
+			Assert(mapped_tables[i] == 0);
+#endif
+	}
+
+	/* The new indexes must be visible for deletion. */
+	CommandCounterIncrement();
+
+	/* Close the old heap but keep lock until transaction commit. */
+	table_close(OldHeap, NoLock);
+	/* Close the new heap. (We didn't have to open its indexes). */
+	table_close(NewHeap, NoLock);
+
+	/* Cleanup what we don't need anymore. (And close the identity index.) */
+	pfree(chgdst.ident_key);
+	free_index_insert_state(chgdst.iistate);
+
+	/*
+	 * Swap the relations and their TOAST relations and TOAST indexes. This
+	 * also drops the new relation and its indexes.
+	 *
+	 * (System catalogs are currently not supported.)
+	 */
+	Assert(!is_system_catalog);
+	finish_heap_swap(old_table_oid, new_table_oid,
+					 is_system_catalog,
+					 false,		/* swap_toast_by_content */
+					 false, true, false,
+					 frozenXid, cutoffMulti,
+					 relpersistence);
+}
+
+/*
+ * Build indexes on NewHeap according to those on OldHeap.
+ *
+ * OldIndexes is the list of index OIDs on OldHeap. The contained indexes end
+ * up locked using ShareUpdateExclusiveLock.
+ *
+ * A list of OIDs of the corresponding indexes created on NewHeap is
+ * returned. The order of items does match, so we can use these arrays to swap
+ * index storage.
+ */
+static List *
+build_new_indexes(Relation NewHeap, Relation OldHeap, List *OldIndexes)
+{
+	List	   *result = NIL;
+
+	pgstat_progress_update_param(PROGRESS_REPACK_PHASE,
+								 PROGRESS_REPACK_PHASE_REBUILD_INDEX);
+
+	foreach_oid(ind_oid, OldIndexes)
+	{
+		Oid			ind_oid_new;
+		char	   *newName;
+		Relation	ind;
+
+		ind = index_open(ind_oid, ShareUpdateExclusiveLock);
+
+		newName = ChooseRelationName(get_rel_name(ind_oid),
+									 NULL,
+									 "repacknew",
+									 get_rel_namespace(ind->rd_index->indrelid),
+									 false);
+		ind_oid_new = index_create_copy(NewHeap, ind_oid,
+										ind->rd_rel->reltablespace, newName,
+										false);
+		result = lappend_oid(result, ind_oid_new);
+
+		index_close(ind, NoLock);
+	}
+
+	return result;
+}
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 81a55a33ef2..ebc70f5bead 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -892,7 +892,7 @@ refresh_by_match_merge(Oid matviewOid, Oid tempOid, Oid relowner,
 static void
 refresh_by_heap_swap(Oid matviewOid, Oid OIDNewHeap, char relpersistence)
 {
-	finish_heap_swap(matviewOid, OIDNewHeap, false, false, true, true,
+	finish_heap_swap(matviewOid, OIDNewHeap, false, false, true, true, true,
 					 RecentXmin, ReadNextMultiXactId(), relpersistence);
 }
 
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index f976c0e5c7e..296387c7889 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6025,6 +6025,7 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
 			finish_heap_swap(tab->relid, OIDNewHeap,
 							 false, false, true,
 							 !OidIsValid(tab->newTableSpace),
+							 true,
 							 RecentXmin,
 							 ReadNextMultiXactId(),
 							 persistence);
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index aea998260e1..bce24d0f804 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -126,7 +126,7 @@ static void vac_truncate_clog(TransactionId frozenXID,
 							  TransactionId lastSaneFrozenXid,
 							  MultiXactId lastSaneMinMulti);
 static bool vacuum_rel(Oid relid, RangeVar *relation, VacuumParams params,
-					   BufferAccessStrategy bstrategy);
+					   BufferAccessStrategy bstrategy, bool isTopLevel);
 static double compute_parallel_delay(void);
 static VacOptValue get_vacoptval_from_boolean(DefElem *def);
 static bool vac_tid_reaped(ItemPointer itemptr, void *state);
@@ -629,7 +629,8 @@ vacuum(List *relations, const VacuumParams params, BufferAccessStrategy bstrateg
 
 			if (params.options & VACOPT_VACUUM)
 			{
-				if (!vacuum_rel(vrel->oid, vrel->relation, params, bstrategy))
+				if (!vacuum_rel(vrel->oid, vrel->relation, params, bstrategy,
+								isTopLevel))
 					continue;
 			}
 
@@ -1999,7 +2000,7 @@ vac_truncate_clog(TransactionId frozenXID,
  */
 static bool
 vacuum_rel(Oid relid, RangeVar *relation, VacuumParams params,
-		   BufferAccessStrategy bstrategy)
+		   BufferAccessStrategy bstrategy, bool isTopLevel)
 {
 	LOCKMODE	lmode;
 	Relation	rel;
@@ -2290,7 +2291,7 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams params,
 
 			/* VACUUM FULL is a variant of REPACK; see cluster.c */
 			cluster_rel(REPACK_COMMAND_VACUUMFULL, rel, InvalidOid,
-						&cluster_params);
+						&cluster_params, isTopLevel);
 			/* cluster_rel closes the relation, but keeps lock */
 
 			rel = NULL;
@@ -2333,7 +2334,8 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams params,
 		toast_vacuum_params.options |= VACOPT_PROCESS_MAIN;
 		toast_vacuum_params.toast_parent = relid;
 
-		vacuum_rel(toast_relid, NULL, toast_vacuum_params, bstrategy);
+		vacuum_rel(toast_relid, NULL, toast_vacuum_params, bstrategy,
+				   isTopLevel);
 	}
 
 	/*
diff --git a/src/backend/meson.build b/src/backend/meson.build
index 712a857cdb4..3e43edf48a0 100644
--- a/src/backend/meson.build
+++ b/src/backend/meson.build
@@ -194,5 +194,6 @@ pg_test_mod_args = pg_mod_args + {
 subdir('jit/llvm')
 subdir('replication/libpqwalreceiver')
 subdir('replication/pgoutput')
+subdir('replication/pgoutput_repack')
 subdir('snowball')
 subdir('utils/mb/conversion_procs')
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index 32af1249610..887873c93ac 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -33,6 +33,7 @@
 #include "access/xlogreader.h"
 #include "access/xlogrecord.h"
 #include "catalog/pg_control.h"
+#include "commands/cluster.h"
 #include "replication/decode.h"
 #include "replication/logical.h"
 #include "replication/message.h"
@@ -420,7 +421,8 @@ heap2_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 	{
 		case XLOG_HEAP2_MULTI_INSERT:
 			if (SnapBuildProcessChange(builder, xid, buf->origptr) &&
-				!ctx->fast_forward)
+				!ctx->fast_forward &&
+				!change_useless_for_repack(buf))
 				DecodeMultiInsert(ctx, buf);
 			break;
 		case XLOG_HEAP2_NEW_CID:
@@ -467,6 +469,15 @@ heap_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 	TransactionId xid = XLogRecGetXid(buf->record);
 	SnapBuild  *builder = ctx->snapshot_builder;
 
+	/*
+	 * XXX Should we return here if change_useless_for_repack() returns true,
+	 * instead of calling the function below? Unlike the fast-forward case, we
+	 * shouldn't need the base snapshot for the containing transaction until
+	 * we receive a change that belongs to the table being REPACKed. Thus it
+	 * should be fine to skip SnapBuildProcessChange(), and therefore
+	 * reorderbuffer.c can create the transaction later.
+	 */
+
 	ReorderBufferProcessXid(ctx->reorder, xid, buf->origptr);
 
 	/*
@@ -484,7 +495,8 @@ heap_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 	{
 		case XLOG_HEAP_INSERT:
 			if (SnapBuildProcessChange(builder, xid, buf->origptr) &&
-				!ctx->fast_forward)
+				!ctx->fast_forward &&
+				!change_useless_for_repack(buf))
 				DecodeInsert(ctx, buf);
 			break;
 
@@ -496,19 +508,22 @@ heap_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 		case XLOG_HEAP_HOT_UPDATE:
 		case XLOG_HEAP_UPDATE:
 			if (SnapBuildProcessChange(builder, xid, buf->origptr) &&
-				!ctx->fast_forward)
+				!ctx->fast_forward &&
+				!change_useless_for_repack(buf))
 				DecodeUpdate(ctx, buf);
 			break;
 
 		case XLOG_HEAP_DELETE:
 			if (SnapBuildProcessChange(builder, xid, buf->origptr) &&
-				!ctx->fast_forward)
+				!ctx->fast_forward &&
+				!change_useless_for_repack(buf))
 				DecodeDelete(ctx, buf);
 			break;
 
 		case XLOG_HEAP_TRUNCATE:
 			if (SnapBuildProcessChange(builder, xid, buf->origptr) &&
-				!ctx->fast_forward)
+				!ctx->fast_forward &&
+				!change_useless_for_repack(buf))
 				DecodeTruncate(ctx, buf);
 			break;
 
@@ -524,7 +539,8 @@ heap_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 
 		case XLOG_HEAP_CONFIRM:
 			if (SnapBuildProcessChange(builder, xid, buf->origptr) &&
-				!ctx->fast_forward)
+				!ctx->fast_forward &&
+				!change_useless_for_repack(buf))
 				DecodeSpecConfirm(ctx, buf);
 			break;
 
@@ -1021,6 +1037,15 @@ DecodeDelete(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
 
 	xlrec = (xl_heap_delete *) XLogRecGetData(r);
 
+	/*
+	 * Ignore changes which are considered useless for logical
+	 * decoding. Currently such changes are created by REPACK (CONCURRENTLY)
+	 * when replays DELETE commands on the new table (which is not yet visible
+	 * to other transactions).
+	 */
+	if (xlrec->flags & XLH_DELETE_NO_LOGICAL)
+		return;
+
 	/* only interested in our database */
 	XLogRecGetBlockTag(r, 0, &target_locator, NULL, NULL);
 	if (target_locator.dbOid != ctx->slot->data.database)
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index a738ad8a864..ffe6aa7f7bb 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -486,6 +486,27 @@ SnapBuildInitialSnapshot(SnapBuild *builder)
 	return SnapBuildMVCCFromHistoric(snap, true);
 }
 
+/*
+ * Build an MVCC snapshot for the initial data load performed by REPACK
+ * CONCURRENTLY command.
+ *
+ * The snapshot will only be used to scan one particular relation, which is
+ * treated like a catalog (therefore ->building_full_snapshot is not
+ * important), and the caller should already have a replication slot setup (so
+ * we do not set MyProc->xmin). XXX Do we yet need to add some restrictions?
+ */
+Snapshot
+SnapBuildInitialSnapshotForRepack(SnapBuild *builder)
+{
+	Snapshot	snap;
+
+	Assert(builder->state == SNAPBUILD_CONSISTENT);
+	Assert(builder->building_full_snapshot);
+
+	snap = SnapBuildBuildSnapshot(builder);
+	return SnapBuildMVCCFromHistoric(snap, false);
+}
+
 /*
  * Turn a historic MVCC snapshot into an ordinary MVCC snapshot.
  *
diff --git a/src/backend/replication/pgoutput_repack/Makefile b/src/backend/replication/pgoutput_repack/Makefile
new file mode 100644
index 00000000000..4efeb713b70
--- /dev/null
+++ b/src/backend/replication/pgoutput_repack/Makefile
@@ -0,0 +1,32 @@
+#-------------------------------------------------------------------------
+#
+# Makefile--
+#    Makefile for src/backend/replication/pgoutput_repack
+#
+# IDENTIFICATION
+#    src/backend/replication/pgoutput_repack
+#
+#-------------------------------------------------------------------------
+
+subdir = src/backend/replication/pgoutput_repack
+top_builddir = ../../../..
+include $(top_builddir)/src/Makefile.global
+
+OBJS = \
+	$(WIN32RES) \
+	pgoutput_repack.o
+PGFILEDESC = "pgoutput_repack - logical replication output plugin for REPACK command"
+NAME = pgoutput_repack
+
+all: all-shared-lib
+
+include $(top_srcdir)/src/Makefile.shlib
+
+install: all installdirs install-lib
+
+installdirs: installdirs-lib
+
+uninstall: uninstall-lib
+
+clean distclean: clean-lib
+	rm -f $(OBJS)
diff --git a/src/backend/replication/pgoutput_repack/meson.build b/src/backend/replication/pgoutput_repack/meson.build
new file mode 100644
index 00000000000..133e865a4a0
--- /dev/null
+++ b/src/backend/replication/pgoutput_repack/meson.build
@@ -0,0 +1,18 @@
+# Copyright (c) 2022-2024, PostgreSQL Global Development Group
+
+pgoutput_repack_sources = files(
+  'pgoutput_repack.c',
+)
+
+if host_system == 'windows'
+  pgoutput_repack_sources += rc_lib_gen.process(win32ver_rc, extra_args: [
+    '--NAME', 'pgoutput_repack',
+    '--FILEDESC', 'pgoutput_repack - logical replication output plugin for REPACK command',])
+endif
+
+pgoutput_repack = shared_module('pgoutput_repack',
+  pgoutput_repack_sources,
+  kwargs: pg_mod_args,
+)
+
+backend_targets += pgoutput_repack
diff --git a/src/backend/replication/pgoutput_repack/pgoutput_repack.c b/src/backend/replication/pgoutput_repack/pgoutput_repack.c
new file mode 100644
index 00000000000..6b54ea040ac
--- /dev/null
+++ b/src/backend/replication/pgoutput_repack/pgoutput_repack.c
@@ -0,0 +1,239 @@
+/*-------------------------------------------------------------------------
+ *
+ * pgoutput_repack.c
+ *		Logical Replication output plugin for REPACK command
+ *
+ * Copyright (c) 2012-2026, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		  src/backend/replication/pgoutput_repack/pgoutput_repack.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/heaptoast.h"
+#include "commands/cluster.h"
+#include "replication/snapbuild.h"
+#include "utils/memutils.h"
+
+PG_MODULE_MAGIC;
+
+static void plugin_startup(LogicalDecodingContext *ctx,
+						   OutputPluginOptions *opt, bool is_init);
+static void plugin_shutdown(LogicalDecodingContext *ctx);
+static void plugin_begin_txn(LogicalDecodingContext *ctx,
+							 ReorderBufferTXN *txn);
+static void plugin_commit_txn(LogicalDecodingContext *ctx,
+							  ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
+static void plugin_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
+						  Relation rel, ReorderBufferChange *change);
+static void store_change(LogicalDecodingContext *ctx,
+						 ConcurrentChangeKind kind, HeapTuple tuple);
+
+void
+_PG_output_plugin_init(OutputPluginCallbacks *cb)
+{
+	cb->startup_cb = plugin_startup;
+	cb->begin_cb = plugin_begin_txn;
+	cb->change_cb = plugin_change;
+	cb->commit_cb = plugin_commit_txn;
+	cb->shutdown_cb = plugin_shutdown;
+}
+
+
+/* initialize this plugin */
+static void
+plugin_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
+			   bool is_init)
+{
+	ctx->output_plugin_private = NULL;
+
+	/* Probably unnecessary, as we don't use the SQL interface ... */
+	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
+
+	if (ctx->output_plugin_options != NIL)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("This plugin does not expect any options")));
+	}
+}
+
+static void
+plugin_shutdown(LogicalDecodingContext *ctx)
+{
+}
+
+/*
+ * As we don't release the slot during processing of particular table, there's
+ * no room for SQL interface, even for debugging purposes. Therefore we need
+ * neither OutputPluginPrepareWrite() nor OutputPluginWrite() in the plugin
+ * callbacks. (Although we might want to write custom callbacks, this API
+ * seems to be unnecessarily generic for our purposes.)
+ */
+
+/* BEGIN callback */
+static void
+plugin_begin_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
+{
+}
+
+/* COMMIT callback */
+static void
+plugin_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
+				  XLogRecPtr commit_lsn)
+{
+}
+
+/*
+ * Callback for individual changed tuples
+ */
+static void
+plugin_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
+			  Relation relation, ReorderBufferChange *change)
+{
+	RepackDecodingState *dstate;
+
+	dstate = (RepackDecodingState *) ctx->output_writer_private;
+
+	/* Only interested in one particular relation. */
+	if (relation->rd_id != dstate->relid)
+		return;
+
+	/* Decode entry depending on its type */
+	switch (change->action)
+	{
+		case REORDER_BUFFER_CHANGE_INSERT:
+			{
+				HeapTuple	newtuple;
+
+				newtuple = change->data.tp.newtuple;
+
+				/*
+				 * Identity checks in the main function should have made this
+				 * impossible.
+				 */
+				if (newtuple == NULL)
+					elog(ERROR, "Incomplete insert info.");
+
+				store_change(ctx, CHANGE_INSERT, newtuple);
+			}
+			break;
+		case REORDER_BUFFER_CHANGE_UPDATE:
+			{
+				HeapTuple	oldtuple,
+							newtuple;
+
+				oldtuple = change->data.tp.oldtuple;
+				newtuple = change->data.tp.newtuple;
+
+				if (newtuple == NULL)
+					elog(ERROR, "Incomplete update info.");
+
+				if (oldtuple != NULL)
+					store_change(ctx, CHANGE_UPDATE_OLD, oldtuple);
+
+				store_change(ctx, CHANGE_UPDATE_NEW, newtuple);
+			}
+			break;
+		case REORDER_BUFFER_CHANGE_DELETE:
+			{
+				HeapTuple	oldtuple;
+
+				oldtuple = change->data.tp.oldtuple;
+
+				if (oldtuple == NULL)
+					elog(ERROR, "Incomplete delete info.");
+
+				store_change(ctx, CHANGE_DELETE, oldtuple);
+			}
+			break;
+		default:
+			/*
+			 * Should not come here. This includes TRUNCATE of the table being
+			 * processed. heap_decode() cannot check the file locator easily,
+			 * but we assume that TRUNCATE uses AccessExclusiveLock on the
+			 * table so it should not occur during REPACK (CONCURRENTLY).
+			 */
+			Assert(false);
+			break;
+	}
+}
+
+/* Store concurrent data change. */
+static void
+store_change(LogicalDecodingContext *ctx, ConcurrentChangeKind kind,
+			 HeapTuple tuple)
+{
+	RepackDecodingState *dstate;
+	char	   *change_raw;
+	ConcurrentChange change;
+	bool		flattened = false;
+	Size		size;
+	Datum		values[1];
+	bool		isnull[1];
+	char	   *dst;
+
+	dstate = (RepackDecodingState *) ctx->output_writer_private;
+
+	size = VARHDRSZ + SizeOfConcurrentChange;
+
+	/*
+	 * ReorderBufferCommit() stores the TOAST chunks in its private memory
+	 * context and frees them after having called apply_change().  Therefore
+	 * we need flat copy (including TOAST) that we eventually copy into the
+	 * memory context which is available to decode_concurrent_changes().
+	 */
+	if (HeapTupleHasExternal(tuple))
+	{
+		/*
+		 * toast_flatten_tuple_to_datum() might be more convenient but we
+		 * don't want the decompression it does.
+		 */
+		tuple = toast_flatten_tuple(tuple, dstate->tupdesc);
+		flattened = true;
+	}
+
+	size += tuple->t_len;
+	if (size >= MaxAllocSize)
+		elog(ERROR, "Change is too big.");
+
+	/* Construct the change. */
+	change_raw = (char *) palloc0(size);
+	SET_VARSIZE(change_raw, size);
+
+	/*
+	 * Since the varlena alignment might not be sufficient for the structure,
+	 * set the fields in a local instance and remember where it should
+	 * eventually be copied.
+	 */
+	change.kind = kind;
+	dst = (char *) VARDATA(change_raw);
+
+	/*
+	 * Copy the tuple.
+	 *
+	 * Note: change->tup_data.t_data must be fixed on retrieval!
+	 */
+	memcpy(&change.tup_data, tuple, sizeof(HeapTupleData));
+	memcpy(dst, &change, SizeOfConcurrentChange);
+	dst += SizeOfConcurrentChange;
+	memcpy(dst, tuple->t_data, tuple->t_len);
+
+	/* The data has been copied. */
+	if (flattened)
+		pfree(tuple);
+
+	/* Store as tuple of 1 bytea column. */
+	values[0] = PointerGetDatum(change_raw);
+	isnull[0] = false;
+	tuplestore_putvalues(dstate->tstore, dstate->tupdesc_change,
+						 values, isnull);
+
+	/* Accounting. */
+	dstate->nchanges++;
+
+	/* Cleanup. */
+	pfree(change_raw);
+}
diff --git a/src/backend/storage/lmgr/generate-lwlocknames.pl b/src/backend/storage/lmgr/generate-lwlocknames.pl
index b49007167b0..2e7f1054e62 100644
--- a/src/backend/storage/lmgr/generate-lwlocknames.pl
+++ b/src/backend/storage/lmgr/generate-lwlocknames.pl
@@ -162,7 +162,7 @@ while (<$lwlocklist>)
 
 die
   "$wait_event_lwlocks[$lwlock_count] defined in wait_event_names.txt but "
-  . " missing from lwlocklist.h"
+  . "missing from lwlocklist.h"
   if $lwlock_count < scalar @wait_event_lwlocks;
 
 die
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 3af1b366adf..fdf3427b43f 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -214,7 +214,6 @@ static List *exportedSnapshots = NIL;
 
 /* Prototypes for local functions */
 static void UnregisterSnapshotNoOwner(Snapshot snapshot);
-static void FreeSnapshot(Snapshot snapshot);
 static void SnapshotResetXmin(void);
 
 /* ResourceOwner callbacks to track snapshot references */
@@ -659,7 +658,7 @@ CopySnapshot(Snapshot snapshot)
  * FreeSnapshot
  *		Free the memory associated with a snapshot.
  */
-static void
+void
 FreeSnapshot(Snapshot snapshot)
 {
 	Assert(snapshot->regd_count == 0);
diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index 2a1bb47ff03..0ec0f4c4790 100644
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -5121,8 +5121,8 @@ match_previous_words(int pattern_id,
 		 * one word, so the above test is correct.
 		 */
 		if (ends_with(prev_wd, '(') || ends_with(prev_wd, ','))
-			COMPLETE_WITH("ANALYZE", "VERBOSE");
-		else if (TailMatches("ANALYZE", "VERBOSE"))
+			COMPLETE_WITH("ANALYZE", "CONCURRENTLY", "VERBOSE");
+		else if (TailMatches("ANALYZE", "CONCURRENTLY", "VERBOSE"))
 			COMPLETE_WITH("ON", "OFF");
 	}
 
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 3c0961ab36b..f3cf4e1f487 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -361,14 +361,15 @@ extern void heap_multi_insert(Relation relation, TupleTableSlot **slots,
 							  BulkInsertState bistate);
 extern TM_Result heap_delete(Relation relation, const ItemPointerData *tid,
 							 CommandId cid, Snapshot crosscheck, bool wait,
-							 TM_FailureData *tmfd, bool changingPart);
+							 TM_FailureData *tmfd, bool changingPart,
+							 bool wal_logical);
 extern void heap_finish_speculative(Relation relation, const ItemPointerData *tid);
 extern void heap_abort_speculative(Relation relation, const ItemPointerData *tid);
 extern TM_Result heap_update(Relation relation, const ItemPointerData *otid,
 							 HeapTuple newtup,
 							 CommandId cid, Snapshot crosscheck, bool wait,
 							 TM_FailureData *tmfd, LockTupleMode *lockmode,
-							 TU_UpdateIndexes *update_indexes);
+							 TU_UpdateIndexes *update_indexes, bool wal_logical);
 extern TM_Result heap_lock_tuple(Relation relation, HeapTuple tuple,
 								 CommandId cid, LockTupleMode mode, LockWaitPolicy wait_policy,
 								 bool follow_updates,
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index ce3566ba949..f1f5495556b 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -104,6 +104,8 @@
 #define XLH_DELETE_CONTAINS_OLD_KEY				(1<<2)
 #define XLH_DELETE_IS_SUPER						(1<<3)
 #define XLH_DELETE_IS_PARTITION_MOVE			(1<<4)
+/* See heap_delete() */
+#define XLH_DELETE_NO_LOGICAL					(1<<5)
 
 /* convenience macro for checking whether any form of old tuple was logged */
 #define XLH_DELETE_CONTAINS_OLD						\
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7260b7b3d52..14928cd04a1 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -22,6 +22,7 @@
 #include "access/xact.h"
 #include "commands/vacuum.h"
 #include "executor/tuptable.h"
+#include "replication/logical.h"
 #include "storage/read_stream.h"
 #include "utils/rel.h"
 #include "utils/snapshot.h"
@@ -629,6 +630,8 @@ typedef struct TableAmRoutine
 											  Relation OldIndex,
 											  bool use_sort,
 											  TransactionId OldestXmin,
+											  Snapshot snapshot,
+											  LogicalDecodingContext *decoding_ctx,
 											  TransactionId *xid_cutoff,
 											  MultiXactId *multi_cutoff,
 											  double *num_tuples,
@@ -1658,6 +1661,10 @@ table_relation_copy_data(Relation rel, const RelFileLocator *newrlocator)
  *   not needed for the relation's AM
  * - *xid_cutoff - ditto
  * - *multi_cutoff - ditto
+ * - snapshot - if != NULL, ignore data changes done by transactions that this
+ *	 (MVCC) snapshot considers still in-progress or in the future.
+ * - decoding_ctx - logical decoding context, to capture concurrent data
+ *   changes.
  *
  * Output parameters:
  * - *xid_cutoff - rel's new relfrozenxid value, may be invalid
@@ -1670,6 +1677,8 @@ table_relation_copy_for_cluster(Relation OldTable, Relation NewTable,
 								Relation OldIndex,
 								bool use_sort,
 								TransactionId OldestXmin,
+								Snapshot snapshot,
+								LogicalDecodingContext *decoding_ctx,
 								TransactionId *xid_cutoff,
 								MultiXactId *multi_cutoff,
 								double *num_tuples,
@@ -1678,6 +1687,7 @@ table_relation_copy_for_cluster(Relation OldTable, Relation NewTable,
 {
 	OldTable->rd_tableam->relation_copy_for_cluster(OldTable, NewTable, OldIndex,
 													use_sort, OldestXmin,
+													snapshot, decoding_ctx,
 													xid_cutoff, multi_cutoff,
 													num_tuples, tups_vacuumed,
 													tups_recently_dead);
diff --git a/src/include/commands/cluster.h b/src/include/commands/cluster.h
index 28741988478..6a5c476294a 100644
--- a/src/include/commands/cluster.h
+++ b/src/include/commands/cluster.h
@@ -13,10 +13,15 @@
 #ifndef CLUSTER_H
 #define CLUSTER_H
 
+#include "nodes/execnodes.h"
 #include "nodes/parsenodes.h"
 #include "parser/parse_node.h"
+#include "replication/decode.h"
+#include "replication/logical.h"
 #include "storage/lock.h"
 #include "utils/relcache.h"
+#include "utils/resowner.h"
+#include "utils/tuplestore.h"
 
 
 /* flag bits for ClusterParams->options */
@@ -25,6 +30,8 @@
 #define CLUOPT_RECHECK_ISCLUSTERED 0x04 /* recheck relation state for
 										 * indisclustered */
 #define CLUOPT_ANALYZE 0x08		/* do an ANALYZE */
+#define CLUOPT_CONCURRENT 0x10	/* allow concurrent data changes */
+
 
 /* options for CLUSTER */
 typedef struct ClusterParams
@@ -33,10 +40,84 @@ typedef struct ClusterParams
 } ClusterParams;
 
 
+/*
+ * The following definitions are used by REPACK CONCURRENTLY.
+ */
+
+typedef enum
+{
+	CHANGE_INSERT,
+	CHANGE_UPDATE_OLD,
+	CHANGE_UPDATE_NEW,
+	CHANGE_DELETE
+} ConcurrentChangeKind;
+
+typedef struct ConcurrentChange
+{
+	/* See the enum above. */
+	ConcurrentChangeKind kind;
+
+	/*
+	 * The actual tuple.
+	 *
+	 * The tuple data follows the ConcurrentChange structure. Before use make
+	 * sure the tuple is correctly aligned (ConcurrentChange can be stored as
+	 * bytea) and that tuple->t_data is fixed.
+	 */
+	HeapTupleData tup_data;
+} ConcurrentChange;
+
+#define SizeOfConcurrentChange (offsetof(ConcurrentChange, tup_data) + \
+								sizeof(HeapTupleData))
+
+/*
+ * Logical decoding state.
+ *
+ * Here we store the data changes that we decode from WAL while the table
+ * contents is being copied to a new storage. Also the necessary metadata
+ * needed to apply these changes to the table is stored here.
+ */
+typedef struct RepackDecodingState
+{
+	/* The relation whose changes we're decoding. */
+	Oid			relid;
+
+	/* Replication slot name. */
+	NameData	slotname;
+
+	/*
+	 * Decoded changes are stored here. Although we try to avoid excessive
+	 * batches, it can happen that the changes need to be stored to disk. The
+	 * tuplestore does this transparently.
+	 */
+	Tuplestorestate *tstore;
+
+	/* The current number of changes in tstore. */
+	double		nchanges;
+
+	/*
+	 * Descriptor to store the ConcurrentChange structure serialized (bytea).
+	 * We can't store the tuple directly because tuplestore only supports
+	 * minimum tuple and we may need to transfer OID system column from the
+	 * output plugin. Also we need to transfer the change kind, so it's better
+	 * to put everything in the structure than to use 2 tuplestores "in
+	 * parallel".
+	 */
+	TupleDesc	tupdesc_change;
+
+	/* Tuple descriptor needed to update indexes. */
+	TupleDesc	tupdesc;
+
+	/* Slot to retrieve data from tstore. */
+	TupleTableSlot *tsslot;
+
+	ResourceOwner resowner;
+} RepackDecodingState;
+
 extern void ExecRepack(ParseState *pstate, RepackStmt *stmt, bool isTopLevel);
 
 extern void cluster_rel(RepackCommand command, Relation OldHeap, Oid indexOid,
-						ClusterParams *params);
+						ClusterParams *params, bool isTopLevel);
 extern void check_index_is_clusterable(Relation OldHeap, Oid indexOid,
 									   LOCKMODE lockmode);
 extern void mark_index_clustered(Relation rel, Oid indexOid, bool is_internal);
@@ -48,8 +129,13 @@ extern void finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
 							 bool swap_toast_by_content,
 							 bool check_constraints,
 							 bool is_internal,
+							 bool reindex,
 							 TransactionId frozenXid,
 							 MultiXactId cutoffMulti,
 							 char newrelpersistence);
 
+extern bool am_decoding_for_repack(void);
+extern bool change_useless_for_repack(XLogRecordBuffer *buf);
+extern void repack_decode_concurrent_changes(LogicalDecodingContext *ctx,
+											 XLogRecPtr end_of_wal);
 #endif							/* CLUSTER_H */
diff --git a/src/include/commands/progress.h b/src/include/commands/progress.h
index f00e39b937d..4445724a463 100644
--- a/src/include/commands/progress.h
+++ b/src/include/commands/progress.h
@@ -86,10 +86,12 @@
 #define PROGRESS_REPACK_PHASE					1
 #define PROGRESS_REPACK_INDEX_RELID				2
 #define PROGRESS_REPACK_HEAP_TUPLES_SCANNED		3
-#define PROGRESS_REPACK_HEAP_TUPLES_WRITTEN		4
-#define PROGRESS_REPACK_TOTAL_HEAP_BLKS			5
-#define PROGRESS_REPACK_HEAP_BLKS_SCANNED		6
-#define PROGRESS_REPACK_INDEX_REBUILD_COUNT		7
+#define PROGRESS_REPACK_HEAP_TUPLES_INSERTED	4
+#define PROGRESS_REPACK_HEAP_TUPLES_UPDATED		5
+#define PROGRESS_REPACK_HEAP_TUPLES_DELETED		6
+#define PROGRESS_REPACK_TOTAL_HEAP_BLKS			7
+#define PROGRESS_REPACK_HEAP_BLKS_SCANNED		8
+#define PROGRESS_REPACK_INDEX_REBUILD_COUNT		9
 
 /*
  * Phases of repack (as advertised via PROGRESS_REPACK_PHASE).
@@ -98,9 +100,10 @@
 #define PROGRESS_REPACK_PHASE_INDEX_SCAN_HEAP	2
 #define PROGRESS_REPACK_PHASE_SORT_TUPLES		3
 #define PROGRESS_REPACK_PHASE_WRITE_NEW_HEAP	4
-#define PROGRESS_REPACK_PHASE_SWAP_REL_FILES	5
-#define PROGRESS_REPACK_PHASE_REBUILD_INDEX		6
-#define PROGRESS_REPACK_PHASE_FINAL_CLEANUP		7
+#define PROGRESS_REPACK_PHASE_CATCH_UP			5
+#define PROGRESS_REPACK_PHASE_SWAP_REL_FILES	6
+#define PROGRESS_REPACK_PHASE_REBUILD_INDEX		7
+#define PROGRESS_REPACK_PHASE_FINAL_CLEANUP		8
 
 /* Progress parameters for CREATE INDEX */
 /* 3, 4 and 5 reserved for "waitfor" metrics */
diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h
index 34383dea776..5ee267d1c90 100644
--- a/src/include/replication/snapbuild.h
+++ b/src/include/replication/snapbuild.h
@@ -73,6 +73,7 @@ extern void FreeSnapshotBuilder(SnapBuild *builder);
 extern void SnapBuildSnapDecRefcount(Snapshot snap);
 
 extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder);
+extern Snapshot SnapBuildInitialSnapshotForRepack(SnapBuild *builder);
 extern Snapshot SnapBuildMVCCFromHistoric(Snapshot snapshot, bool in_place);
 extern const char *SnapBuildExportSnapshot(SnapBuild *builder);
 extern void SnapBuildClearExportedSnapshot(void);
diff --git a/src/include/storage/lockdefs.h b/src/include/storage/lockdefs.h
index b73bb5618e6..3785b009808 100644
--- a/src/include/storage/lockdefs.h
+++ b/src/include/storage/lockdefs.h
@@ -36,8 +36,8 @@ typedef int LOCKMODE;
 #define AccessShareLock			1	/* SELECT */
 #define RowShareLock			2	/* SELECT FOR UPDATE/FOR SHARE */
 #define RowExclusiveLock		3	/* INSERT, UPDATE, DELETE */
-#define ShareUpdateExclusiveLock 4	/* VACUUM (non-FULL), ANALYZE, CREATE
-									 * INDEX CONCURRENTLY */
+#define ShareUpdateExclusiveLock 4	/* VACUUM (non-exclusive), ANALYZE, CREATE
+									 * INDEX CONCURRENTLY, REPACK CONCURRENTLY */
 #define ShareLock				5	/* CREATE INDEX (WITHOUT CONCURRENTLY) */
 #define ShareRowExclusiveLock	6	/* like EXCLUSIVE MODE, but allows ROW
 									 * SHARE */
diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h
index de824945f0b..0eb8ced76d3 100644
--- a/src/include/utils/snapmgr.h
+++ b/src/include/utils/snapmgr.h
@@ -64,6 +64,8 @@ extern Snapshot GetLatestSnapshot(void);
 extern void SnapshotSetCommandId(CommandId curcid);
 
 extern Snapshot CopySnapshot(Snapshot snapshot);
+extern void FreeSnapshot(Snapshot snapshot);
+
 extern Snapshot GetCatalogSnapshot(Oid relid);
 extern Snapshot GetNonHistoricCatalogSnapshot(Oid relid);
 extern void InvalidateCatalogSnapshot(void);
diff --git a/src/test/modules/injection_points/Makefile b/src/test/modules/injection_points/Makefile
index a41d781f8c9..2cd7d87c533 100644
--- a/src/test/modules/injection_points/Makefile
+++ b/src/test/modules/injection_points/Makefile
@@ -14,6 +14,8 @@ REGRESS_OPTS = --dlpath=$(top_builddir)/src/test/regress
 
 ISOLATION = basic \
 	    inplace \
+	    repack \
+	    repack_toast \
 	    syscache-update-pruned \
 	    heap_lock_update
 
diff --git a/src/test/modules/injection_points/expected/repack.out b/src/test/modules/injection_points/expected/repack.out
new file mode 100644
index 00000000000..b575e9052ee
--- /dev/null
+++ b/src/test/modules/injection_points/expected/repack.out
@@ -0,0 +1,113 @@
+Parsed test spec with 2 sessions
+
+starting permutation: wait_before_lock change_existing change_new change_subxact1 change_subxact2 check2 wakeup_before_lock check1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step wait_before_lock: 
+	REPACK (CONCURRENTLY) repack_test USING INDEX repack_test_pkey;
+ <waiting ...>
+step change_existing: 
+	UPDATE repack_test SET i=10 where i=1;
+	UPDATE repack_test SET j=20 where i=2;
+	UPDATE repack_test SET i=30 where i=3;
+	UPDATE repack_test SET i=40 where i=30;
+	DELETE FROM repack_test WHERE i=4;
+
+step change_new: 
+	INSERT INTO repack_test(i, j) VALUES (5, 5), (6, 6), (7, 7), (8, 8);
+	UPDATE repack_test SET i=50 where i=5;
+	UPDATE repack_test SET j=60 where i=6;
+	DELETE FROM repack_test WHERE i=7;
+
+step change_subxact1: 
+	BEGIN;
+	INSERT INTO repack_test(i, j) VALUES (100, 100);
+	SAVEPOINT s1;
+	UPDATE repack_test SET i=101 where i=100;
+	SAVEPOINT s2;
+	UPDATE repack_test SET i=102 where i=101;
+	COMMIT;
+
+step change_subxact2: 
+	BEGIN;
+	SAVEPOINT s1;
+	INSERT INTO repack_test(i, j) VALUES (110, 110);
+	ROLLBACK TO SAVEPOINT s1;
+	INSERT INTO repack_test(i, j) VALUES (110, 111);
+	COMMIT;
+
+step check2: 
+	INSERT INTO relfilenodes(node)
+	SELECT relfilenode FROM pg_class WHERE relname='repack_test';
+
+	SELECT i, j FROM repack_test ORDER BY i, j;
+
+	INSERT INTO data_s2(i, j)
+	SELECT i, j FROM repack_test;
+
+  i|  j
+---+---
+  2| 20
+  6| 60
+  8|  8
+ 10|  1
+ 40|  3
+ 50|  5
+102|100
+110|111
+(8 rows)
+
+step wakeup_before_lock: 
+	SELECT injection_points_wakeup('repack-concurrently-before-lock');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step wait_before_lock: <... completed>
+step check1: 
+	INSERT INTO relfilenodes(node)
+	SELECT relfilenode FROM pg_class WHERE relname='repack_test';
+
+	SELECT count(DISTINCT node) FROM relfilenodes;
+
+	SELECT i, j FROM repack_test ORDER BY i, j;
+
+	INSERT INTO data_s1(i, j)
+	SELECT i, j FROM repack_test;
+
+	SELECT count(*)
+	FROM data_s1 d1 FULL JOIN data_s2 d2 USING (i, j)
+	WHERE d1.i ISNULL OR d2.i ISNULL;
+
+count
+-----
+    2
+(1 row)
+
+  i|  j
+---+---
+  2| 20
+  6| 60
+  8|  8
+ 10|  1
+ 40|  3
+ 50|  5
+102|100
+110|111
+(8 rows)
+
+count
+-----
+    0
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
diff --git a/src/test/modules/injection_points/expected/repack_toast.out b/src/test/modules/injection_points/expected/repack_toast.out
new file mode 100644
index 00000000000..4f866a74e32
--- /dev/null
+++ b/src/test/modules/injection_points/expected/repack_toast.out
@@ -0,0 +1,64 @@
+Parsed test spec with 2 sessions
+
+starting permutation: wait_before_lock change check2 wakeup_before_lock check1
+injection_points_attach
+-----------------------
+                       
+(1 row)
+
+step wait_before_lock: 
+	REPACK (CONCURRENTLY) repack_test;
+ <waiting ...>
+step change: 
+	UPDATE repack_test SET j=get_long_string() where i=2;
+	DELETE FROM repack_test WHERE i=3;
+	INSERT INTO repack_test(i, j) VALUES (4, get_long_string());
+
+step check2: 
+	INSERT INTO relfilenodes(node)
+	SELECT c2.relfilenode
+	FROM pg_class c1 JOIN pg_class c2 ON c2.oid = c1.oid OR c2.oid = c1.reltoastrelid
+	WHERE c1.relname='repack_test';
+
+	INSERT INTO data_s2(i, j)
+	SELECT i, j FROM repack_test;
+
+step wakeup_before_lock: 
+	SELECT injection_points_wakeup('repack-concurrently-before-lock');
+
+injection_points_wakeup
+-----------------------
+                       
+(1 row)
+
+step wait_before_lock: <... completed>
+step check1: 
+	INSERT INTO relfilenodes(node)
+	SELECT c2.relfilenode
+	FROM pg_class c1 JOIN pg_class c2 ON c2.oid = c1.oid OR c2.oid = c1.reltoastrelid
+	WHERE c1.relname='repack_test';
+
+	SELECT count(DISTINCT node) FROM relfilenodes;
+
+	INSERT INTO data_s1(i, j)
+	SELECT i, j FROM repack_test;
+
+	SELECT count(*)
+	FROM data_s1 d1 FULL JOIN data_s2 d2 USING (i, j)
+	WHERE d1.i ISNULL OR d2.i ISNULL;
+
+count
+-----
+    4
+(1 row)
+
+count
+-----
+    0
+(1 row)
+
+injection_points_detach
+-----------------------
+                       
+(1 row)
+
diff --git a/src/test/modules/injection_points/meson.build b/src/test/modules/injection_points/meson.build
index fcc85414515..a414abb924b 100644
--- a/src/test/modules/injection_points/meson.build
+++ b/src/test/modules/injection_points/meson.build
@@ -45,6 +45,8 @@ tests += {
     'specs': [
       'basic',
       'inplace',
+      'repack',
+      'repack_toast',
       'syscache-update-pruned',
       'heap_lock_update',
     ],
diff --git a/src/test/modules/injection_points/specs/repack.spec b/src/test/modules/injection_points/specs/repack.spec
new file mode 100644
index 00000000000..d727a9b056b
--- /dev/null
+++ b/src/test/modules/injection_points/specs/repack.spec
@@ -0,0 +1,142 @@
+# REPACK (CONCURRENTLY) ... USING INDEX ...;
+setup
+{
+	CREATE EXTENSION injection_points;
+
+	CREATE TABLE repack_test(i int PRIMARY KEY, j int);
+	INSERT INTO repack_test(i, j) VALUES (1, 1), (2, 2), (3, 3), (4, 4);
+
+	CREATE TABLE relfilenodes(node oid);
+
+	CREATE TABLE data_s1(i int, j int);
+	CREATE TABLE data_s2(i int, j int);
+}
+
+teardown
+{
+	DROP TABLE repack_test;
+	DROP EXTENSION injection_points;
+
+	DROP TABLE relfilenodes;
+	DROP TABLE data_s1;
+	DROP TABLE data_s2;
+}
+
+session s1
+setup
+{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('repack-concurrently-before-lock', 'wait');
+}
+# Perform the initial load and wait for s2 to do some data changes.
+step wait_before_lock
+{
+	REPACK (CONCURRENTLY) repack_test USING INDEX repack_test_pkey;
+}
+# Check the table from the perspective of s1.
+#
+# Besides the contents, we also check that relfilenode has changed.
+
+# Have each session write the contents into a table and use FULL JOIN to check
+# if the outputs are identical.
+step check1
+{
+	INSERT INTO relfilenodes(node)
+	SELECT relfilenode FROM pg_class WHERE relname='repack_test';
+
+	SELECT count(DISTINCT node) FROM relfilenodes;
+
+	SELECT i, j FROM repack_test ORDER BY i, j;
+
+	INSERT INTO data_s1(i, j)
+	SELECT i, j FROM repack_test;
+
+	SELECT count(*)
+	FROM data_s1 d1 FULL JOIN data_s2 d2 USING (i, j)
+	WHERE d1.i ISNULL OR d2.i ISNULL;
+}
+teardown
+{
+	SELECT injection_points_detach('repack-concurrently-before-lock');
+}
+
+session s2
+# Change the existing data. UPDATE changes both key and non-key columns. Also
+# update one row twice to test whether tuple version generated by this session
+# can be found.
+step change_existing
+{
+	UPDATE repack_test SET i=10 where i=1;
+	UPDATE repack_test SET j=20 where i=2;
+	UPDATE repack_test SET i=30 where i=3;
+	UPDATE repack_test SET i=40 where i=30;
+	DELETE FROM repack_test WHERE i=4;
+}
+# Insert new rows and UPDATE / DELETE some of them. Again, update both key and
+# non-key column.
+step change_new
+{
+	INSERT INTO repack_test(i, j) VALUES (5, 5), (6, 6), (7, 7), (8, 8);
+	UPDATE repack_test SET i=50 where i=5;
+	UPDATE repack_test SET j=60 where i=6;
+	DELETE FROM repack_test WHERE i=7;
+}
+
+# When applying concurrent data changes, we should see the effects of an
+# in-progress subtransaction.
+#
+# XXX Not sure this test is useful now - it was designed for the patch that
+# preserves tuple visibility and which therefore modifies
+# TransactionIdIsCurrentTransactionId().
+step change_subxact1
+{
+	BEGIN;
+	INSERT INTO repack_test(i, j) VALUES (100, 100);
+	SAVEPOINT s1;
+	UPDATE repack_test SET i=101 where i=100;
+	SAVEPOINT s2;
+	UPDATE repack_test SET i=102 where i=101;
+	COMMIT;
+}
+
+# When applying concurrent data changes, we should not see the effects of a
+# rolled back subtransaction.
+#
+# XXX Is this test useful? See above.
+step change_subxact2
+{
+	BEGIN;
+	SAVEPOINT s1;
+	INSERT INTO repack_test(i, j) VALUES (110, 110);
+	ROLLBACK TO SAVEPOINT s1;
+	INSERT INTO repack_test(i, j) VALUES (110, 111);
+	COMMIT;
+}
+
+# Check the table from the perspective of s2.
+step check2
+{
+	INSERT INTO relfilenodes(node)
+	SELECT relfilenode FROM pg_class WHERE relname='repack_test';
+
+	SELECT i, j FROM repack_test ORDER BY i, j;
+
+	INSERT INTO data_s2(i, j)
+	SELECT i, j FROM repack_test;
+}
+step wakeup_before_lock
+{
+	SELECT injection_points_wakeup('repack-concurrently-before-lock');
+}
+
+# Test if data changes introduced while one session is performing REPACK
+# CONCURRENTLY find their way into the table.
+permutation
+	wait_before_lock
+	change_existing
+	change_new
+	change_subxact1
+	change_subxact2
+	check2
+	wakeup_before_lock
+	check1
diff --git a/src/test/modules/injection_points/specs/repack_toast.spec b/src/test/modules/injection_points/specs/repack_toast.spec
new file mode 100644
index 00000000000..b48abf21450
--- /dev/null
+++ b/src/test/modules/injection_points/specs/repack_toast.spec
@@ -0,0 +1,105 @@
+# REPACK (CONCURRENTLY);
+#
+# Test handling of TOAST. At the same time, no tuplesort.
+setup
+{
+	CREATE EXTENSION injection_points;
+
+	-- Return a string that needs to be TOASTed.
+	CREATE FUNCTION get_long_string()
+	RETURNS text
+	LANGUAGE sql as $$
+		SELECT string_agg(chr(65 + trunc(25 * random())::int), '')
+		FROM generate_series(1, 2048) s(x);
+	$$;
+
+	CREATE TABLE repack_test(i int PRIMARY KEY, j text);
+	INSERT INTO repack_test(i, j) VALUES (1, get_long_string()),
+		(2, get_long_string()), (3, get_long_string());
+
+	CREATE TABLE relfilenodes(node oid);
+
+	CREATE TABLE data_s1(i int, j text);
+	CREATE TABLE data_s2(i int, j text);
+}
+
+teardown
+{
+	DROP TABLE repack_test;
+	DROP EXTENSION injection_points;
+	DROP FUNCTION get_long_string();
+
+	DROP TABLE relfilenodes;
+	DROP TABLE data_s1;
+	DROP TABLE data_s2;
+}
+
+session s1
+setup
+{
+	SELECT injection_points_set_local();
+	SELECT injection_points_attach('repack-concurrently-before-lock', 'wait');
+}
+# Perform the initial load and wait for s2 to do some data changes.
+step wait_before_lock
+{
+	REPACK (CONCURRENTLY) repack_test;
+}
+# Check the table from the perspective of s1.
+#
+# Besides the contents, we also check that relfilenode has changed.
+
+# Have each session write the contents into a table and use FULL JOIN to check
+# if the outputs are identical.
+step check1
+{
+	INSERT INTO relfilenodes(node)
+	SELECT c2.relfilenode
+	FROM pg_class c1 JOIN pg_class c2 ON c2.oid = c1.oid OR c2.oid = c1.reltoastrelid
+	WHERE c1.relname='repack_test';
+
+	SELECT count(DISTINCT node) FROM relfilenodes;
+
+	INSERT INTO data_s1(i, j)
+	SELECT i, j FROM repack_test;
+
+	SELECT count(*)
+	FROM data_s1 d1 FULL JOIN data_s2 d2 USING (i, j)
+	WHERE d1.i ISNULL OR d2.i ISNULL;
+}
+teardown
+{
+    SELECT injection_points_detach('repack-concurrently-before-lock');
+}
+
+session s2
+step change
+{
+	UPDATE repack_test SET j=get_long_string() where i=2;
+	DELETE FROM repack_test WHERE i=3;
+	INSERT INTO repack_test(i, j) VALUES (4, get_long_string());
+}
+# Check the table from the perspective of s2.
+step check2
+{
+	INSERT INTO relfilenodes(node)
+	SELECT c2.relfilenode
+	FROM pg_class c1 JOIN pg_class c2 ON c2.oid = c1.oid OR c2.oid = c1.reltoastrelid
+	WHERE c1.relname='repack_test';
+
+	INSERT INTO data_s2(i, j)
+	SELECT i, j FROM repack_test;
+}
+step wakeup_before_lock
+{
+	SELECT injection_points_wakeup('repack-concurrently-before-lock');
+}
+
+# Test if data changes introduced while one session is performing REPACK
+# CONCURRENTLY find their way into the table.
+permutation
+	wait_before_lock
+	change
+	check2
+	wakeup_before_lock
+	check1
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 48461550636..470920f0d16 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2014,7 +2014,7 @@ pg_stat_progress_cluster| SELECT pid,
     phase,
     repack_index_relid AS cluster_index_relid,
     heap_tuples_scanned,
-    heap_tuples_written,
+    (heap_tuples_inserted + heap_tuples_updated) AS heap_tuples_written,
     heap_blks_total,
     heap_blks_scanned,
     index_rebuild_count
@@ -2094,17 +2094,20 @@ pg_stat_progress_repack| SELECT s.pid,
             WHEN 2 THEN 'index scanning heap'::text
             WHEN 3 THEN 'sorting tuples'::text
             WHEN 4 THEN 'writing new heap'::text
-            WHEN 5 THEN 'swapping relation files'::text
-            WHEN 6 THEN 'rebuilding index'::text
-            WHEN 7 THEN 'performing final cleanup'::text
+            WHEN 5 THEN 'catch-up'::text
+            WHEN 6 THEN 'swapping relation files'::text
+            WHEN 7 THEN 'rebuilding index'::text
+            WHEN 8 THEN 'performing final cleanup'::text
             ELSE NULL::text
         END AS phase,
     (s.param3)::oid AS repack_index_relid,
     s.param4 AS heap_tuples_scanned,
-    s.param5 AS heap_tuples_written,
-    s.param6 AS heap_blks_total,
-    s.param7 AS heap_blks_scanned,
-    s.param8 AS index_rebuild_count
+    s.param5 AS heap_tuples_inserted,
+    s.param6 AS heap_tuples_updated,
+    s.param7 AS heap_tuples_deleted,
+    s.param8 AS heap_blks_total,
+    s.param9 AS heap_blks_scanned,
+    s.param10 AS index_rebuild_count
    FROM (pg_stat_get_progress_info('REPACK'::text) s(pid, datid, relid, param1, param2, param3, param4, param5, param6, param7, param8, param9, param10, param11, param12, param13, param14, param15, param16, param17, param18, param19, param20)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)));
 pg_stat_progress_vacuum| SELECT s.pid,
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 6c4af1c210d..2676823d2a7 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -420,6 +420,7 @@ CatCacheHeader
 CatalogId
 CatalogIdMapEntry
 CatalogIndexState
+ChangeDest
 ChangeVarNodes_callback
 ChangeVarNodes_context
 ChannelName
@@ -497,6 +498,8 @@ CompressFileHandle
 CompressionLocation
 CompressorState
 ComputeXidHorizonsResult
+ConcurrentChange
+ConcurrentChangeKind
 ConditionVariable
 ConditionVariableMinimallyPadded
 ConditionalStack
@@ -1278,6 +1281,7 @@ IndexElem
 IndexFetchHeapData
 IndexFetchTableData
 IndexInfo
+IndexInsertState
 IndexList
 IndexOnlyScan
 IndexOnlyScanState
@@ -2576,6 +2580,7 @@ ReorderBufferTupleCidKey
 ReorderBufferUpdateProgressTxnCB
 ReorderTuple
 RepackCommand
+RepackDecodingState
 RepackStmt
 ReparameterizeForeignPathByChild_function
 ReplOriginId
-- 
2.47.3

