Re: Reduce heap tuple header size II - Mailing list pgsql-patches

On Fri, 21 Jun 2002 12:45:48 -0400 (EDT), Bruce Momjian <pgman@candle.pha.pa.us> wrote:
>> > Yes, there are some good ones there, but the idea that somehow they are
>> > all going to hit in the same release seems unlikely.  I say let's do
>> > some now, some later, and move ahead.

I (strongly :-)) agree.

>Well, that is a different argument than initially.  So, it is a valid
>patch, but we have to decide when to apply it.
>
>We can easily hold it until we near release of 7.3.  If pg_upgrade is in
>good shape _and_ no other format changes are required, we can  hold it
>for 7.4.  What happens if 7.4 doesn't have any format changes?
>
>However, if we have other changes or pg_upgrade isn't going to work, we
>can apply it in August.

But what, if the patch causes or reveals a well hidden bug, possibly
somewhere else in the code?  I'd vote for applying it now, so that in
August it already has undergone some testing.  You can always patch -R
before going beta...

>(Manfred, you can be sure I will not lose this patch.)

Thanks.  Anyway, lose it!  Here is a new version.

>So, we have to decide if we apply it now or delay it for later in 7.3,
>or for >=7.4.

Why not let the users decide?  With this new version of the patch they
can
    configure --enable-pg72format
if this patch is the only thing that stops pg_upgrade from working and
if they want to use pg_upgrade.

>My personal vote is that we apply it now, and perhaps try some of the
>other format changes we were going to make.

And with #ifdef PG72FORMAT we can introduce them without very much
risk.  One thing that's still missing is we'd need two entries in
catversion.h.

Servus
 Manfred

diff -u ../base/INSTALL ./INSTALL
--- ../base/INSTALL    2002-01-31 01:46:26.000000000 +0100
+++ ./INSTALL    2002-06-25 15:59:03.000000000 +0200
@@ -283,6 +283,13 @@
           Enables single-byte character set recode support. See the
           Administrator's Guide about this feature.

+     --enable-pg72format
+
+          Enables version 7.2 page format, giving you a better chance of
+          converting existing databases by pg_upgrade. Do not use this
+          feature, if you are just starting to use PostgreSQL or if you
+          plan to upgrade via pg_dump/restore.
+
      --enable-multibyte

           Allows the use of multibyte character encodings (including
Common subdirectories: ../base/config and ./config
diff -u ../base/configure ./configure
--- ../base/configure    2002-05-29 14:42:20.000000000 +0200
+++ ./configure    2002-06-25 15:51:18.000000000 +0200
@@ -1652,6 +1652,44 @@


 #
+# Version 7.2 page format (--enable-pg72format)
+#
+echo "$as_me:$LINENO: checking whether to build with version 7.2 page format" >&5
+echo $ECHO_N "checking whether to build with version 7.2 page format... $ECHO_C" >&6
+
+
+# Check whether --enable-pg72format or --disable-pg72format was given.
+if test "${enable_pg72format+set}" = set; then
+  enableval="$enable_pg72format"
+
+  case $enableval in
+    yes)
+
+cat >>confdefs.h <<\_ACEOF
+#define PG72FORMAT 1
+_ACEOF
+
+      ;;
+    no)
+      :
+      ;;
+    *)
+      { { echo "$as_me:$LINENO: error: no argument expected for --enable-pg72format option" >&5
+echo "$as_me: error: no argument expected for --enable-pg72format option" >&2;}
+   { (exit 1); exit 1; }; }
+      ;;
+  esac
+
+else
+  enable_pg72format=no
+
+fi;
+
+echo "$as_me:$LINENO: result: $enable_pg72format" >&5
+echo "${ECHO_T}$enable_pg72format" >&6
+
+
+#
 # Multibyte support
 #
 MULTIBYTE=SQL_ASCII
diff -u ../base/configure.in ./configure.in
--- ../base/configure.in    2002-05-29 14:42:20.000000000 +0200
+++ ./configure.in    2002-06-25 15:51:15.000000000 +0200
@@ -162,6 +162,16 @@


 #
+# Version 7.2 page format (--enable-pg72format)
+#
+AC_MSG_CHECKING([whether to build with version 7.2 page format])
+PGAC_ARG_BOOL(enable, pg72format, no, [  --enable-pg72format     enable version 7.2 page format],
+              [AC_DEFINE([PG72FORMAT], 1,
+                         [Set to 1 if you want version 7.2 page format (--enable-pg72format)])])
+AC_MSG_RESULT([$enable_pg72format])
+
+
+#
 # Multibyte support
 #
 MULTIBYTE=SQL_ASCII
diff -ru ../base/src/backend/access/heap/heapam.c src/backend/access/heap/heapam.c
--- ../base/src/backend/access/heap/heapam.c    2002-06-17 10:11:31.000000000 +0200
+++ src/backend/access/heap/heapam.c    2002-06-17 22:35:32.000000000 +0200
@@ -2204,7 +2204,7 @@
         htup->t_infomask = HEAP_XMAX_INVALID | xlhdr.mask;
         HeapTupleHeaderSetXmin(htup, record->xl_xid);
         HeapTupleHeaderSetCmin(htup, FirstCommandId);
-        HeapTupleHeaderSetXmax(htup, InvalidTransactionId);
+        HeapTupleHeaderSetXmaxInvalid(htup);
         HeapTupleHeaderSetCmax(htup, FirstCommandId);

         offnum = PageAddItem(page, (Item) htup, newlen, offnum,
diff -ru ../base/src/include/access/htup.h src/include/access/htup.h
--- ../base/src/include/access/htup.h    2002-06-17 10:11:32.000000000 +0200
+++ src/include/access/htup.h    2002-06-25 16:14:37.000000000 +0200
@@ -57,15 +57,33 @@
  * Also note that we omit the nulls bitmap if t_infomask shows that there
  * are no nulls in the tuple.
  */
+/*
+** We store five "virtual" fields Xmin, Cmin, Xmax, Cmax, and Xvac
+** in three physical fields t_xmin, t_cid, t_xmax:
+** CommandId     Cmin;        insert CID stamp
+** CommandId     Cmax;        delete CommandId stamp
+** TransactionId Xmin;        insert XID stamp
+** TransactionId Xmax;        delete XID stamp
+** TransactionId Xvac;        used by VACCUUM
+**
+** This assumes, that a CommandId can be stored in a TransactionId.
+*/
 typedef struct HeapTupleHeaderData
 {
     Oid            t_oid;            /* OID of this tuple -- 4 bytes */

+#ifdef PG72FORMAT
+    /* v7.2: Xvac is stored in t_cmin */
     CommandId    t_cmin;            /* insert CID stamp -- 4 bytes each */
     CommandId    t_cmax;            /* delete CommandId stamp */

     TransactionId t_xmin;        /* insert XID stamp -- 4 bytes each */
     TransactionId t_xmax;        /* delete XID stamp */
+#else
+    TransactionId t_xmin;        /* Xmin -- 4 bytes each */
+    TransactionId t_cid;        /* Cmin, Cmax, Xvac */
+    TransactionId t_xmax;        /* Xmax, Cmax */
+#endif

     ItemPointerData t_ctid;        /* current TID of this or newer tuple */

@@ -75,7 +93,7 @@

     uint8        t_hoff;            /* sizeof header incl. bitmap, padding */

-    /* ^ - 31 bytes - ^ */
+    /* ^ - 27 (v7.3) or 31 (v7.2) bytes - ^ */

     bits8        t_bits[1];        /* bitmap of NULLs -- VARIABLE LENGTH */

@@ -96,6 +114,8 @@
                                          * attribute(s) */
 #define HEAP_HASEXTENDED        0x000C    /* the two above combined */

+#define HEAP_XMIN_IS_XMAX        0x0040    /* created and deleted in the */
+                                        /* same transaction */
 #define HEAP_XMAX_UNLOGGED        0x0080    /* to lock tuple for update */
                                         /* without logging */
 #define HEAP_XMIN_COMMITTED        0x0100    /* t_xmin committed */
@@ -108,6 +128,7 @@
                                          * vacuum */
 #define HEAP_MOVED_IN            0x8000    /* moved from another place by
                                          * vacuum */
+#define HEAP_MOVED (HEAP_MOVED_OFF | HEAP_MOVED_IN)

 #define HEAP_XACT_MASK            0xFFF0    /* visibility-related bits */

@@ -116,8 +137,11 @@
 /* HeapTupleHeader accessor macros */

 #define HeapTupleHeaderGetXmin(tup) \
-    ((tup)->t_xmin)
+( \
+    (tup)->t_xmin \
+)

+#ifdef PG72FORMAT
 #define HeapTupleHeaderGetXmax(tup) \
     ((tup)->t_xmax)

@@ -163,6 +187,98 @@
     AssertMacro((tup)->t_infomask & (HEAP_MOVED_IN | HEAP_MOVED_OFF)), \
     TransactionIdStore((xid), (TransactionId *) &((tup)->t_cmin)) \
 )
+#else
+#define HeapTupleHeaderGetXmax(tup) \
+( \
+    ((tup)->t_infomask & HEAP_XMIN_IS_XMAX) ? \
+        (tup)->t_xmin \
+    : \
+        (tup)->t_xmax \
+)
+
+/* no AssertMacro, because this is read as a system-defined attribute */
+#define HeapTupleHeaderGetCmin(tup) \
+( \
+    ((tup)->t_infomask & HEAP_MOVED) ? \
+        FirstCommandId \
+    : \
+    ( \
+        ((tup)->t_infomask & (HEAP_XMIN_IS_XMAX | HEAP_XMAX_INVALID)) ? \
+            (CommandId) (tup)->t_cid \
+        : \
+            FirstCommandId \
+    ) \
+)
+
+#define HeapTupleHeaderGetCmax(tup) \
+( \
+    ((tup)->t_infomask & HEAP_MOVED) ? \
+        FirstCommandId \
+    : \
+    ( \
+        ((tup)->t_infomask & (HEAP_XMIN_IS_XMAX | HEAP_XMAX_INVALID)) ? \
+            (CommandId) (tup)->t_xmax \
+        : \
+            (CommandId) (tup)->t_cid \
+    ) \
+)
+
+#define HeapTupleHeaderGetXvac(tup) \
+( \
+    AssertMacro((tup)->t_infomask & HEAP_MOVED), \
+    (tup)->t_cid \
+)
+
+
+#define HeapTupleHeaderSetXmin(tup, xid) \
+( \
+    TransactionIdStore((xid), &(tup)->t_xmin) \
+)
+
+#define HeapTupleHeaderSetXminInvalid(tup) \
+do { \
+    (tup)->t_infomask &= ~HEAP_XMIN_IS_XMAX; \
+    StoreInvalidTransactionId(&(tup)->t_xmin); \
+} while (0)
+
+#define HeapTupleHeaderSetXmax(tup, xid) \
+do { \
+    if (TransactionIdEquals((tup)->t_xmin, (xid))) \
+        (tup)->t_infomask |= HEAP_XMIN_IS_XMAX; \
+    else \
+    { \
+        (tup)->t_infomask &= ~HEAP_XMIN_IS_XMAX; \
+        TransactionIdStore((xid), &(tup)->t_xmax); \
+    } \
+} while (0)
+
+#define HeapTupleHeaderSetXmaxInvalid(tup) \
+do { \
+    (tup)->t_infomask &= ~HEAP_XMIN_IS_XMAX; \
+    StoreInvalidTransactionId(&(tup)->t_xmax); \
+} while (0)
+
+#define HeapTupleHeaderSetCmin(tup, cid) \
+do { \
+    Assert(!((tup)->t_infomask & HEAP_MOVED)); \
+    TransactionIdStore((TransactionId) (cid), &(tup)->t_cid); \
+} while (0)
+
+#define HeapTupleHeaderSetCmax(tup, cid) \
+do { \
+    Assert(!((tup)->t_infomask & HEAP_MOVED)); \
+    if ((tup)->t_infomask & HEAP_XMIN_IS_XMAX) \
+        TransactionIdStore((TransactionId) (cid), &(tup)->t_xmax); \
+    else \
+        TransactionIdStore((TransactionId) (cid), &(tup)->t_cid); \
+} while (0)
+
+#define HeapTupleHeaderSetXvac(tup, xid) \
+do { \
+    Assert((tup)->t_infomask & HEAP_MOVED); \
+    TransactionIdStore((xid), &(tup)->t_cid); \
+} while (0)
+#endif


 /*
diff -ru ../base/src/include/pg_config.h.in src/include/pg_config.h.in
--- ../base/src/include/pg_config.h.in    2002-06-17 21:04:03.000000000 +0200
+++ src/include/pg_config.h.in    2002-06-25 16:02:40.000000000 +0200
@@ -39,6 +39,9 @@
 /* Set to 1 if you want cyrillic recode (--enable-recode) */
 #undef CYR_RECODE

+/* Set to 1 if you want version 7.2 page format (--enable-pg72format) */
+#undef PG72FORMAT
+
 /* Set to 1 if you want to use multibyte characters (--enable-multibyte) */
 #undef MULTIBYTE