Re: Removing pg_pltemplate and creating "trustable" extensions - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Removing pg_pltemplate and creating "trustable" extensions
Date
Msg-id 28987.1573331052@sss.pgh.pa.us
Whole thread Raw
In response to Re: Removing pg_pltemplate and creating "trustable" extensions  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Removing pg_pltemplate and creating "trustable" extensions  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
I wrote:
> Stephen Frost <sfrost@snowman.net> writes:
>> Really?  Why do you think that DB ownership shouldn't be enough for
>> this, for trusted extensions?

> DB owners have never been particularly highly privileged in the past.
> I think that suddenly saying they can install extensions is moving
> the understanding of that privilege level quite a bit.  Although
> admittedly, the precedent of trusted PLs would point to allowing them
> to install trusted extensions without further ado.  So maybe a
> different take on this is "allow installing trusted extensions if you
> are DB owner *or* have the pg_install_trusted_extensions role"?

After sleeping on it, I'm liking that idea; it's simple, and it
preserves the existing behavior that DB owners can install trusted PLs
without any extra permissions.  Now, if we follow this up by marking
most of contrib as trusted, we'd be expanding that existing privilege.
But I think that's all right: I don't recall anybody ever complaining
that they wanted to prevent DB owners from installing trusted PLs, and
I do recall people wishing that it didn't take superuser to install
the other stuff.

Accordingly, here's a patchset that does it like that.

I decided after looking at the existing default role names that
"pg_install_trusted_extension" (no plural) was more consistent
with the existing names than adding an "s".  I don't find that
precedent particularly charming, but it's what we've got.

I also renamed the extension property from "trustable" to "trusted".
There are at least a couple of reasons to be dissatisfied with that:

(1) There's potential for confusion between the notion of a trusted
extension and that of a trusted PL; those properties do roughly
similar things, but they're not exactly equivalent.  I didn't think
this was enough of a problem to justify choosing a different name,
but somebody else might think differently.

(2) If we were starting this design from scratch, we'd probably not
have two interrelated boolean properties "superuser" and "trusted",
but one three-state enum property.  The enum approach would likely
be a lot easier to extend if we eventually grow more privilege
levels for extension installation.  I'm not sure whether it's worth
breaking backwards compatibility now to keep our options open for
that, though.  We could preserve extension control file
compatibility easily enough by keeping "superuser = true" and
"superuser = false" as allowed legacy spellings for two values of
an enum property.  But the pg_available_extension_versions view is
a tougher nut.  On the other hand, maybe replacing its "superuser"
column with something else wouldn't really cause many problems.

Other than getting rid of the GUCs in favor of this design,
it's mostly the same patchset as before.  0003 and 0004 haven't
changed at all, and 0002 only differs by adjusting the test case.

            regards, tom lane

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 55694c4..a573dfb 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -8514,7 +8514,15 @@ SCRAM-SHA-256$<replaceable><iteration count></replaceable>:<replaceable>&l
      <row>
       <entry><structfield>superuser</structfield></entry>
       <entry><type>bool</type></entry>
-      <entry>True if only superusers are allowed to install this extension</entry>
+      <entry>True if only superusers are allowed to install this extension
+       (but see <structfield>trusted</structfield>)</entry>
+     </row>
+
+     <row>
+      <entry><structfield>trusted</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry>True if the extension can be installed by non-superusers
+       with appropriate privileges</entry>
      </row>

      <row>
diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml
index a3046f2..e2807d0 100644
--- a/doc/src/sgml/extend.sgml
+++ b/doc/src/sgml/extend.sgml
@@ -576,6 +576,32 @@
         version.  If it is set to <literal>false</literal>, just the privileges
         required to execute the commands in the installation or update script
         are required.
+        This should normally be set to <literal>true</literal> if any of the
+        script commands require superuser privileges.  (Such commands would
+        fail anyway, but it's more user-friendly to give the error up front.)
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><varname>trusted</varname> (<type>boolean</type>)</term>
+      <listitem>
+       <para>
+        This parameter, if set to <literal>true</literal> (which is not the
+        default), allows some non-superusers to install an extension that
+        has <varname>superuser</varname> set to <literal>true</literal>.
+        Specifically, installation will be permitted for the owner of the
+        current database, and for anyone who has been granted
+        the <literal>pg_install_trusted_extension</literal> role.
+        When the user executing <command>CREATE EXTENSION</command> is not
+        a superuser but is allowed to install by virtue of this parameter,
+        then the installation or update script is run as the bootstrap
+        superuser, not as the calling user.
+        This parameter is irrelevant if <varname>superuser</varname> is
+        <literal>false</literal>.
+        Generally, this should not be set true for extensions that could
+        allow access to otherwise-superuser-only abilities, such as
+        filesystem access.
        </para>
       </listitem>
      </varlistentry>
@@ -642,6 +668,18 @@
     </para>

     <para>
+     If the extension script contains the
+     string <literal>@extowner@</literal>, that string is replaced with the
+     (suitably quoted) name of the user calling <command>CREATE
+     EXTENSION</command> or <command>ALTER EXTENSION</command>.  Typically
+     this feature is used by extensions that are marked trusted to assign
+     ownership of selected objects to the calling user rather than the
+     bootstrap superuser.  (One should be careful about doing so, however.
+     For example, assigning ownership of a C-language function to a
+     non-superuser would create a privilege escalation path for that user.)
+    </para>
+
+    <para>
      While the script files can contain any characters allowed by the specified
      encoding, control files should contain only plain ASCII, because there
      is no way for <productname>PostgreSQL</productname> to know what encoding a
diff --git a/doc/src/sgml/ref/create_extension.sgml b/doc/src/sgml/ref/create_extension.sgml
index 36837f9..7cd4346 100644
--- a/doc/src/sgml/ref/create_extension.sgml
+++ b/doc/src/sgml/ref/create_extension.sgml
@@ -47,14 +47,26 @@ CREATE EXTENSION [ IF NOT EXISTS ] <replaceable class="parameter">extension_name
   </para>

   <para>
-   Loading an extension requires the same privileges that would be
-   required to create its component objects.  For most extensions this
-   means superuser or database owner privileges are needed.
    The user who runs <command>CREATE EXTENSION</command> becomes the
    owner of the extension for purposes of later privilege checks, as well
    as the owner of any objects created by the extension's script.
   </para>

+  <para>
+   Loading an extension ordinarily requires the same privileges that would
+   be required to create its component objects.  For many extensions this
+   means superuser privileges are needed.
+   However, if the extension is marked <firstterm>trusted</firstterm> in
+   its control file, then it can be installed by a non-superuser who has
+   suitable privileges (that is, owns the current database or has been
+   granted the <literal>pg_install_trusted_extension</literal> role).  In
+   this case the extension object itself will be owned by the calling user,
+   but the contained objects will be owned by the bootstrap superuser
+   (unless the extension's script explicitly assigns them to the calling
+   user).  This configuration gives the calling user the right to drop the
+   extension, but not to modify individual objects within it.
+  </para>
+
  </refsect1>

  <refsect1>
diff --git a/doc/src/sgml/user-manag.sgml b/doc/src/sgml/user-manag.sgml
index 66f1627..90f637f 100644
--- a/doc/src/sgml/user-manag.sgml
+++ b/doc/src/sgml/user-manag.sgml
@@ -556,6 +556,10 @@ DROP ROLE doomed_role;
        <entry>Allow executing programs on the database server as the user the database runs as with
        COPY and other functions which allow executing a server-side program.</entry>
       </row>
+      <row>
+       <entry>pg_install_trusted_extension</entry>
+       <entry>Allow installation of <quote>trusted</quote> extensions.</entry>
+      </row>
      </tbody>
     </tgroup>
    </table>
@@ -589,6 +593,17 @@ DROP ROLE doomed_role;
   </para>

   <para>
+  The <literal>pg_install_trusted_extension</literal> role allows grantees
+  to install <link linkend="extend-extensions">extensions</link> that are
+  marked <quote>trusted</quote> in their control files.  This is a
+  privilege that is available automatically to database owners, but
+  granting this role allows administrators to let other non-superuser roles
+  do it too.  Generally, unless the <quote>trusted</quote> marking has been
+  applied to extensions incautiously, granting this role carries no large
+  security risk.
+  </para>
+
+  <para>
   Care should be taken when granting these roles to ensure they are only used where
   needed and with the understanding that these roles grant access to privileged
   information.
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 9fe4a47..6560605 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -317,7 +317,8 @@ CREATE VIEW pg_available_extensions AS

 CREATE VIEW pg_available_extension_versions AS
     SELECT E.name, E.version, (X.extname IS NOT NULL) AS installed,
-           E.superuser, E.relocatable, E.schema, E.requires, E.comment
+           E.superuser, E.trusted, E.relocatable,
+           E.schema, E.requires, E.comment
       FROM pg_available_extension_versions() AS E
            LEFT JOIN pg_extension AS X
              ON E.name = X.extname AND E.version = X.extversion;
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index a04b0c9..bf66a1c 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -40,6 +40,7 @@
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/objectaccess.h"
+#include "catalog/pg_authid.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_extension.h"
@@ -84,6 +85,7 @@ typedef struct ExtensionControlFile
     char       *schema;            /* target schema (allowed if !relocatable) */
     bool        relocatable;    /* is ALTER EXTENSION SET SCHEMA supported? */
     bool        superuser;        /* must be superuser to install? */
+    bool        trusted;        /* allow becoming superuser on the fly? */
     int            encoding;        /* encoding of the script file, or -1 */
     List       *requires;        /* names of prerequisite extensions */
 } ExtensionControlFile;
@@ -558,6 +560,14 @@ parse_extension_control_file(ExtensionControlFile *control,
                          errmsg("parameter \"%s\" requires a Boolean value",
                                 item->name)));
         }
+        else if (strcmp(item->name, "trusted") == 0)
+        {
+            if (!parse_bool(item->value, &control->trusted))
+                ereport(ERROR,
+                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+                         errmsg("parameter \"%s\" requires a Boolean value",
+                                item->name)));
+        }
         else if (strcmp(item->name, "encoding") == 0)
         {
             control->encoding = pg_valid_server_encoding(item->value);
@@ -614,6 +624,7 @@ read_extension_control_file(const char *extname)
     control->name = pstrdup(extname);
     control->relocatable = false;
     control->superuser = true;
+    control->trusted = false;
     control->encoding = -1;

     /*
@@ -795,6 +806,27 @@ execute_sql_string(const char *sql)
 }

 /*
+ * Policy function: is the given extension trusted for installation by a
+ * non-superuser?
+ *
+ * (Update the errhint logic below if you change this.)
+ */
+static bool
+extension_is_trusted(ExtensionControlFile *control)
+{
+    /* Never trust unless extension's control file says it's okay */
+    if (!control->trusted)
+        return false;
+    /* Database owner can install */
+    if (pg_database_ownercheck(MyDatabaseId, GetUserId()))
+        return true;
+    /* Members of pg_install_trusted_extension can install */
+    if (has_privs_of_role(GetUserId(), DEFAULT_ROLE_INSTALL_TRUSTED_EXTENSION))
+        return true;
+    return false;
+}
+
+/*
  * Execute the appropriate script file for installing or updating the extension
  *
  * If from_version isn't NULL, it's an update
@@ -806,35 +838,56 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
                          List *requiredSchemas,
                          const char *schemaName, Oid schemaOid)
 {
+    bool        switch_to_superuser = false;
     char       *filename;
+    Oid            save_userid = 0;
+    int            save_sec_context = 0;
     int            save_nestlevel;
     StringInfoData pathbuf;
     ListCell   *lc;

     /*
-     * Enforce superuser-ness if appropriate.  We postpone this check until
-     * here so that the flag is correctly associated with the right script(s)
-     * if it's set in secondary control files.
+     * Enforce superuser-ness if appropriate.  We postpone these checks until
+     * here so that the control flags are correctly associated with the right
+     * script(s) if they happen to be set in secondary control files.
      */
     if (control->superuser && !superuser())
     {
-        if (from_version == NULL)
+        if (extension_is_trusted(control))
+            switch_to_superuser = true;
+        else if (from_version == NULL)
             ereport(ERROR,
                     (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                      errmsg("permission denied to create extension \"%s\"",
                             control->name),
-                     errhint("Must be superuser to create this extension.")));
+                     control->trusted
+                     ? errhint("Must be database owner or member of pg_install_trusted_extension to create this
extension.")
+                     : errhint("Must be superuser to create this extension.")));
         else
             ereport(ERROR,
                     (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                      errmsg("permission denied to update extension \"%s\"",
                             control->name),
-                     errhint("Must be superuser to update this extension.")));
+                     control->trusted
+                     ? errhint("Must be database owner or member of pg_install_trusted_extension to update this
extension.")
+                     : errhint("Must be superuser to update this extension.")));
     }

     filename = get_extension_script_filename(control, from_version, version);

     /*
+     * If installing a trusted extension on behalf of a non-superuser, become
+     * the bootstrap superuser.  (This switch will be cleaned up automatically
+     * if the transaction aborts, as will the GUC changes below.)
+     */
+    if (switch_to_superuser)
+    {
+        GetUserIdAndSecContext(&save_userid, &save_sec_context);
+        SetUserIdAndSecContext(BOOTSTRAP_SUPERUSERID,
+                               save_sec_context | SECURITY_LOCAL_USERID_CHANGE);
+    }
+
+    /*
      * Force client_min_messages and log_min_messages to be at least WARNING,
      * so that we won't spam the user with useless NOTICE messages from common
      * script actions like creating shell types.
@@ -907,6 +960,22 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
                                         CStringGetTextDatum("ng"));

         /*
+         * If the script uses @extowner@, substitute the calling username.
+         */
+        if (strstr(c_sql, "@extowner@"))
+        {
+            Oid            uid = switch_to_superuser ? save_userid : GetUserId();
+            const char *userName = GetUserNameFromId(uid, false);
+            const char *qUserName = quote_identifier(userName);
+
+            t_sql = DirectFunctionCall3Coll(replace_text,
+                                            C_COLLATION_OID,
+                                            t_sql,
+                                            CStringGetTextDatum("@extowner@"),
+                                            CStringGetTextDatum(qUserName));
+        }
+
+        /*
          * If it's not relocatable, substitute the target schema name for
          * occurrences of @extschema@.
          *
@@ -953,6 +1022,12 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
      * Restore the GUC variables we set above.
      */
     AtEOXact_GUC(true, save_nestlevel);
+
+    /*
+     * Restore authentication state if needed.
+     */
+    if (switch_to_superuser)
+        SetUserIdAndSecContext(save_userid, save_sec_context);
 }

 /*
@@ -2113,8 +2188,8 @@ get_available_versions_for_extension(ExtensionControlFile *pcontrol,
     {
         ExtensionVersionInfo *evi = (ExtensionVersionInfo *) lfirst(lc);
         ExtensionControlFile *control;
-        Datum        values[7];
-        bool        nulls[7];
+        Datum        values[8];
+        bool        nulls[8];
         ListCell   *lc2;

         if (!evi->installable)
@@ -2135,24 +2210,26 @@ get_available_versions_for_extension(ExtensionControlFile *pcontrol,
         values[1] = CStringGetTextDatum(evi->name);
         /* superuser */
         values[2] = BoolGetDatum(control->superuser);
+        /* trusted */
+        values[3] = BoolGetDatum(control->trusted);
         /* relocatable */
-        values[3] = BoolGetDatum(control->relocatable);
+        values[4] = BoolGetDatum(control->relocatable);
         /* schema */
         if (control->schema == NULL)
-            nulls[4] = true;
+            nulls[5] = true;
         else
-            values[4] = DirectFunctionCall1(namein,
+            values[5] = DirectFunctionCall1(namein,
                                             CStringGetDatum(control->schema));
         /* requires */
         if (control->requires == NIL)
-            nulls[5] = true;
+            nulls[6] = true;
         else
-            values[5] = convert_requires_to_datum(control->requires);
+            values[6] = convert_requires_to_datum(control->requires);
         /* comment */
         if (control->comment == NULL)
-            nulls[6] = true;
+            nulls[7] = true;
         else
-            values[6] = CStringGetTextDatum(control->comment);
+            values[7] = CStringGetTextDatum(control->comment);

         tuplestore_putvalues(tupstore, tupdesc, values, nulls);

@@ -2180,16 +2257,18 @@ get_available_versions_for_extension(ExtensionControlFile *pcontrol,
                 values[1] = CStringGetTextDatum(evi2->name);
                 /* superuser */
                 values[2] = BoolGetDatum(control->superuser);
+                /* trusted */
+                values[3] = BoolGetDatum(control->trusted);
                 /* relocatable */
-                values[3] = BoolGetDatum(control->relocatable);
+                values[4] = BoolGetDatum(control->relocatable);
                 /* schema stays the same */
                 /* requires */
                 if (control->requires == NIL)
-                    nulls[5] = true;
+                    nulls[6] = true;
                 else
                 {
-                    values[5] = convert_requires_to_datum(control->requires);
-                    nulls[5] = false;
+                    values[6] = convert_requires_to_datum(control->requires);
+                    nulls[6] = false;
                 }
                 /* comment stays the same */

diff --git a/src/include/catalog/pg_authid.dat b/src/include/catalog/pg_authid.dat
index c21f97a..3b04259 100644
--- a/src/include/catalog/pg_authid.dat
+++ b/src/include/catalog/pg_authid.dat
@@ -60,5 +60,10 @@
   rolcreaterole => 'f', rolcreatedb => 'f', rolcanlogin => 'f',
   rolreplication => 'f', rolbypassrls => 'f', rolconnlimit => '-1',
   rolpassword => '_null_', rolvaliduntil => '_null_' },
+{ oid => '9495', oid_symbol => 'DEFAULT_ROLE_INSTALL_TRUSTED_EXTENSION',
+  rolname => 'pg_install_trusted_extension', rolsuper => 'f', rolinherit => 't',
+  rolcreaterole => 'f', rolcreatedb => 'f', rolcanlogin => 'f',
+  rolreplication => 'f', rolbypassrls => 'f', rolconnlimit => '-1',
+  rolpassword => '_null_', rolvaliduntil => '_null_' },

 ]
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 58ea5b9..b50eefb 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -9459,9 +9459,9 @@
   proname => 'pg_available_extension_versions', procost => '10',
   prorows => '100', proretset => 't', provolatile => 's',
   prorettype => 'record', proargtypes => '',
-  proallargtypes => '{name,text,bool,bool,name,_name,text}',
-  proargmodes => '{o,o,o,o,o,o,o}',
-  proargnames => '{name,version,superuser,relocatable,schema,requires,comment}',
+  proallargtypes => '{name,text,bool,bool,bool,name,_name,text}',
+  proargmodes => '{o,o,o,o,o,o,o,o}',
+  proargnames => '{name,version,superuser,trusted,relocatable,schema,requires,comment}',
   prosrc => 'pg_available_extension_versions' },
 { oid => '3084', descr => 'list an extension\'s version update paths',
   proname => 'pg_extension_update_paths', procost => '10', prorows => '100',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 210e9cd..88f63ed 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1311,11 +1311,12 @@ pg_available_extension_versions| SELECT e.name,
     e.version,
     (x.extname IS NOT NULL) AS installed,
     e.superuser,
+    e.trusted,
     e.relocatable,
     e.schema,
     e.requires,
     e.comment
-   FROM (pg_available_extension_versions() e(name, version, superuser, relocatable, schema, requires, comment)
+   FROM (pg_available_extension_versions() e(name, version, superuser, trusted, relocatable, schema, requires,
comment)
      LEFT JOIN pg_extension x ON (((e.name = x.extname) AND (e.version = x.extversion))));
 pg_available_extensions| SELECT e.name,
     e.default_version,
diff --git a/src/pl/plperl/GNUmakefile b/src/pl/plperl/GNUmakefile
index 9b1c514..e4d0a0b 100644
--- a/src/pl/plperl/GNUmakefile
+++ b/src/pl/plperl/GNUmakefile
@@ -55,8 +55,10 @@ endif # win32

 SHLIB_LINK = $(perl_embed_ldflags)

-REGRESS_OPTS = --dbname=$(PL_TESTDB) --load-extension=plperl  --load-extension=plperlu
-REGRESS = plperl plperl_lc plperl_trigger plperl_shared plperl_elog plperl_util plperl_init plperlu plperl_array
plperl_callplperl_transaction 
+REGRESS_OPTS = --dbname=$(PL_TESTDB)
+REGRESS = plperl_setup plperl plperl_lc plperl_trigger plperl_shared \
+    plperl_elog plperl_util plperl_init plperlu plperl_array \
+    plperl_call plperl_transaction
 # if Perl can support two interpreters in one backend,
 # test plperl-and-plperlu cases
 ifneq ($(PERL),)
diff --git a/src/pl/plperl/expected/plperl_setup.out b/src/pl/plperl/expected/plperl_setup.out
new file mode 100644
index 0000000..7cb1f25
--- /dev/null
+++ b/src/pl/plperl/expected/plperl_setup.out
@@ -0,0 +1,60 @@
+--
+-- Install the plperl and plperlu extensions
+--
+-- Before going ahead with the to-be-tested installations, verify that
+-- a non-superuser is allowed to install plperl (but not plperlu) when
+-- suitable permissions have been granted.
+CREATE USER regress_user1;
+CREATE USER regress_user2;
+SET ROLE regress_user1;
+CREATE EXTENSION plperl;  -- fail
+ERROR:  permission denied to create extension "plperl"
+HINT:  Must be database owner or member of pg_install_trusted_extension to create this extension.
+CREATE EXTENSION plperlu;  -- fail
+ERROR:  permission denied to create extension "plperlu"
+HINT:  Must be superuser to create this extension.
+RESET ROLE;
+GRANT pg_install_trusted_extension TO regress_user1;
+SET ROLE regress_user1;
+CREATE EXTENSION plperl;
+CREATE EXTENSION plperlu;  -- fail
+ERROR:  permission denied to create extension "plperlu"
+HINT:  Must be superuser to create this extension.
+CREATE FUNCTION foo1() returns int language plperl as '1;';
+SELECT foo1();
+ foo1
+------
+    1
+(1 row)
+
+-- Should be able to change privileges on the language
+revoke all on language plperl from public;
+SET ROLE regress_user2;
+CREATE FUNCTION foo2() returns int language plperl as '2;';  -- fail
+ERROR:  permission denied for language plperl
+SET ROLE regress_user1;
+grant usage on language plperl to regress_user2;
+SET ROLE regress_user2;
+CREATE FUNCTION foo2() returns int language plperl as '2;';
+SELECT foo2();
+ foo2
+------
+    2
+(1 row)
+
+SET ROLE regress_user1;
+-- Should be able to drop the extension, but not the language per se
+DROP LANGUAGE plperl CASCADE;
+ERROR:  cannot drop language plperl because extension plperl requires it
+HINT:  You can drop extension plperl instead.
+DROP EXTENSION plperl CASCADE;
+NOTICE:  drop cascades to 2 other objects
+DETAIL:  drop cascades to function foo1()
+drop cascades to function foo2()
+-- Clean up
+RESET ROLE;
+DROP USER regress_user1;
+DROP USER regress_user2;
+-- Now install the versions that will be used by subsequent test scripts.
+CREATE EXTENSION plperl;
+CREATE EXTENSION plperlu;
diff --git a/src/pl/plperl/plperl--1.0.sql b/src/pl/plperl/plperl--1.0.sql
index f716ba1..5ff31e7 100644
--- a/src/pl/plperl/plperl--1.0.sql
+++ b/src/pl/plperl/plperl--1.0.sql
@@ -1,11 +1,20 @@
 /* src/pl/plperl/plperl--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION plperl_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE plperl;
+CREATE FUNCTION plperl_inline_handler(internal) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION plperl_validator(oid) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE TRUSTED LANGUAGE plperl
+  HANDLER plperl_call_handler
+  INLINE plperl_inline_handler
+  VALIDATOR plperl_validator;
+
+-- The language object, but not the functions, can be owned by a non-superuser.
+ALTER LANGUAGE plperl OWNER TO @extowner@;

 COMMENT ON LANGUAGE plperl IS 'PL/Perl procedural language';
diff --git a/src/pl/plperl/plperl.control b/src/pl/plperl/plperl.control
index 6faace1..3a2230a 100644
--- a/src/pl/plperl/plperl.control
+++ b/src/pl/plperl/plperl.control
@@ -4,4 +4,5 @@ default_version = '1.0'
 module_pathname = '$libdir/plperl'
 relocatable = false
 schema = pg_catalog
-superuser = false
+superuser = true
+trusted = true
diff --git a/src/pl/plperl/plperlu--1.0.sql b/src/pl/plperl/plperlu--1.0.sql
index 7efb4fb..10d7594 100644
--- a/src/pl/plperl/plperlu--1.0.sql
+++ b/src/pl/plperl/plperlu--1.0.sql
@@ -1,11 +1,17 @@
 /* src/pl/plperl/plperlu--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION plperlu_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE plperlu;
+CREATE FUNCTION plperlu_inline_handler(internal) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION plperlu_validator(oid) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE LANGUAGE plperlu
+  HANDLER plperlu_call_handler
+  INLINE plperlu_inline_handler
+  VALIDATOR plperlu_validator;

 COMMENT ON LANGUAGE plperlu IS 'PL/PerlU untrusted procedural language';
diff --git a/src/pl/plperl/sql/plperl_setup.sql b/src/pl/plperl/sql/plperl_setup.sql
new file mode 100644
index 0000000..9c7b52c
--- /dev/null
+++ b/src/pl/plperl/sql/plperl_setup.sql
@@ -0,0 +1,58 @@
+--
+-- Install the plperl and plperlu extensions
+--
+
+-- Before going ahead with the to-be-tested installations, verify that
+-- a non-superuser is allowed to install plperl (but not plperlu) when
+-- suitable permissions have been granted.
+
+CREATE USER regress_user1;
+CREATE USER regress_user2;
+
+SET ROLE regress_user1;
+
+CREATE EXTENSION plperl;  -- fail
+CREATE EXTENSION plperlu;  -- fail
+
+RESET ROLE;
+
+GRANT pg_install_trusted_extension TO regress_user1;
+
+SET ROLE regress_user1;
+
+CREATE EXTENSION plperl;
+CREATE EXTENSION plperlu;  -- fail
+
+CREATE FUNCTION foo1() returns int language plperl as '1;';
+SELECT foo1();
+
+-- Should be able to change privileges on the language
+revoke all on language plperl from public;
+
+SET ROLE regress_user2;
+
+CREATE FUNCTION foo2() returns int language plperl as '2;';  -- fail
+
+SET ROLE regress_user1;
+
+grant usage on language plperl to regress_user2;
+
+SET ROLE regress_user2;
+
+CREATE FUNCTION foo2() returns int language plperl as '2;';
+SELECT foo2();
+
+SET ROLE regress_user1;
+
+-- Should be able to drop the extension, but not the language per se
+DROP LANGUAGE plperl CASCADE;
+DROP EXTENSION plperl CASCADE;
+
+-- Clean up
+RESET ROLE;
+DROP USER regress_user1;
+DROP USER regress_user2;
+
+-- Now install the versions that will be used by subsequent test scripts.
+CREATE EXTENSION plperl;
+CREATE EXTENSION plperlu;
diff --git a/src/pl/plpgsql/src/plpgsql--1.0.sql b/src/pl/plpgsql/src/plpgsql--1.0.sql
index ab6fa84..6e5b990 100644
--- a/src/pl/plpgsql/src/plpgsql--1.0.sql
+++ b/src/pl/plpgsql/src/plpgsql--1.0.sql
@@ -1,11 +1,20 @@
 /* src/pl/plpgsql/src/plpgsql--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION plpgsql_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE plpgsql;
+CREATE FUNCTION plpgsql_inline_handler(internal) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION plpgsql_validator(oid) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE TRUSTED LANGUAGE plpgsql
+  HANDLER plpgsql_call_handler
+  INLINE plpgsql_inline_handler
+  VALIDATOR plpgsql_validator;
+
+-- The language object, but not the functions, can be owned by a non-superuser.
+ALTER LANGUAGE plpgsql OWNER TO @extowner@;

 COMMENT ON LANGUAGE plpgsql IS 'PL/pgSQL procedural language';
diff --git a/src/pl/plpgsql/src/plpgsql.control b/src/pl/plpgsql/src/plpgsql.control
index b320227..42e764b 100644
--- a/src/pl/plpgsql/src/plpgsql.control
+++ b/src/pl/plpgsql/src/plpgsql.control
@@ -4,4 +4,5 @@ default_version = '1.0'
 module_pathname = '$libdir/plpgsql'
 relocatable = false
 schema = pg_catalog
-superuser = false
+superuser = true
+trusted = true
diff --git a/src/pl/plpython/plpython2u--1.0.sql b/src/pl/plpython/plpython2u--1.0.sql
index 661cc66..69f7477 100644
--- a/src/pl/plpython/plpython2u--1.0.sql
+++ b/src/pl/plpython/plpython2u--1.0.sql
@@ -1,11 +1,17 @@
 /* src/pl/plpython/plpython2u--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION plpython2_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE plpython2u;
+CREATE FUNCTION plpython2_inline_handler(internal) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION plpython2_validator(oid) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE LANGUAGE plpython2u
+  HANDLER plpython2_call_handler
+  INLINE plpython2_inline_handler
+  VALIDATOR plpython2_validator;

 COMMENT ON LANGUAGE plpython2u IS 'PL/Python2U untrusted procedural language';
diff --git a/src/pl/plpython/plpython3u--1.0.sql b/src/pl/plpython/plpython3u--1.0.sql
index c0d6ea8..ba2e6ac 100644
--- a/src/pl/plpython/plpython3u--1.0.sql
+++ b/src/pl/plpython/plpython3u--1.0.sql
@@ -1,11 +1,17 @@
 /* src/pl/plpython/plpython3u--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION plpython3_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE plpython3u;
+CREATE FUNCTION plpython3_inline_handler(internal) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION plpython3_validator(oid) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE LANGUAGE plpython3u
+  HANDLER plpython3_call_handler
+  INLINE plpython3_inline_handler
+  VALIDATOR plpython3_validator;

 COMMENT ON LANGUAGE plpython3u IS 'PL/Python3U untrusted procedural language';
diff --git a/src/pl/plpython/plpythonu--1.0.sql b/src/pl/plpython/plpythonu--1.0.sql
index 4a3e64a..4c6f7c3 100644
--- a/src/pl/plpython/plpythonu--1.0.sql
+++ b/src/pl/plpython/plpythonu--1.0.sql
@@ -1,11 +1,17 @@
 /* src/pl/plpython/plpythonu--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION plpython_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE plpythonu;
+CREATE FUNCTION plpython_inline_handler(internal) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE FUNCTION plpython_validator(oid) RETURNS void
+  STRICT LANGUAGE c AS 'MODULE_PATHNAME';
+
+CREATE LANGUAGE plpythonu
+  HANDLER plpython_call_handler
+  INLINE plpython_inline_handler
+  VALIDATOR plpython_validator;

 COMMENT ON LANGUAGE plpythonu IS 'PL/PythonU untrusted procedural language';
diff --git a/src/pl/tcl/pltcl--1.0.sql b/src/pl/tcl/pltcl--1.0.sql
index 34a68c8..2ed2b92 100644
--- a/src/pl/tcl/pltcl--1.0.sql
+++ b/src/pl/tcl/pltcl--1.0.sql
@@ -1,11 +1,12 @@
 /* src/pl/tcl/pltcl--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION pltcl_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE pltcl;
+CREATE TRUSTED LANGUAGE pltcl
+  HANDLER pltcl_call_handler;
+
+-- The language object, but not the functions, can be owned by a non-superuser.
+ALTER LANGUAGE pltcl OWNER TO @extowner@;

 COMMENT ON LANGUAGE pltcl IS 'PL/Tcl procedural language';
diff --git a/src/pl/tcl/pltcl.control b/src/pl/tcl/pltcl.control
index b9dc1b8..1568c17 100644
--- a/src/pl/tcl/pltcl.control
+++ b/src/pl/tcl/pltcl.control
@@ -4,4 +4,5 @@ default_version = '1.0'
 module_pathname = '$libdir/pltcl'
 relocatable = false
 schema = pg_catalog
-superuser = false
+superuser = true
+trusted = true
diff --git a/src/pl/tcl/pltclu--1.0.sql b/src/pl/tcl/pltclu--1.0.sql
index e05b470..fca869f 100644
--- a/src/pl/tcl/pltclu--1.0.sql
+++ b/src/pl/tcl/pltclu--1.0.sql
@@ -1,11 +1,9 @@
 /* src/pl/tcl/pltclu--1.0.sql */

-/*
- * Currently, all the interesting stuff is done by CREATE LANGUAGE.
- * Later we will probably "dumb down" that command and put more of the
- * knowledge into this script.
- */
+CREATE FUNCTION pltclu_call_handler() RETURNS language_handler
+  LANGUAGE c AS 'MODULE_PATHNAME';

-CREATE LANGUAGE pltclu;
+CREATE LANGUAGE pltclu
+  HANDLER pltclu_call_handler;

 COMMENT ON LANGUAGE pltclu IS 'PL/TclU untrusted procedural language';
diff --git a/doc/src/sgml/ref/create_language.sgml b/doc/src/sgml/ref/create_language.sgml
index 13b28b1..2a9c7e8 100644
--- a/doc/src/sgml/ref/create_language.sgml
+++ b/doc/src/sgml/ref/create_language.sgml
@@ -21,9 +21,9 @@ PostgreSQL documentation

  <refsynopsisdiv>
 <synopsis>
-CREATE [ OR REPLACE ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">name</replaceable>
 CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">name</replaceable>
     HANDLER <replaceable class="parameter">call_handler</replaceable> [ INLINE <replaceable
class="parameter">inline_handler</replaceable>] [ VALIDATOR <replaceable>valfunction</replaceable> ] 
+CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">name</replaceable>
 </synopsis>
  </refsynopsisdiv>

@@ -37,21 +37,6 @@ CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="pa
    defined in this new language.
   </para>

-  <note>
-   <para>
-    As of <productname>PostgreSQL</productname> 9.1, most procedural
-    languages have been made into <quote>extensions</quote>, and should
-    therefore be installed with <xref linkend="sql-createextension"/>
-    not <command>CREATE LANGUAGE</command>.  Direct use of
-    <command>CREATE LANGUAGE</command> should now be confined to
-    extension installation scripts.  If you have a <quote>bare</quote>
-    language in your database, perhaps as a result of an upgrade,
-    you can convert it to an extension using
-    <literal>CREATE EXTENSION <replaceable>langname</replaceable> FROM
-    unpackaged</literal>.
-   </para>
-  </note>
-
   <para>
    <command>CREATE LANGUAGE</command> effectively associates the
    language name with handler function(s) that are responsible for executing
@@ -60,53 +45,32 @@ CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="pa
   </para>

   <para>
-   There are two forms of the <command>CREATE LANGUAGE</command> command.
-   In the first form, the user supplies just the name of the desired
-   language, and the <productname>PostgreSQL</productname> server consults
-   the <link linkend="catalog-pg-pltemplate"><structname>pg_pltemplate</structname></link>
-   system catalog to determine the correct parameters.  In the second form,
-   the user supplies the language parameters along with the language name.
-   The second form can be used to create a language that is not defined in
-   <structname>pg_pltemplate</structname>, but this approach is considered obsolescent.
-  </para>
-
-  <para>
-   When the server finds an entry in the <structname>pg_pltemplate</structname> catalog
-   for the given language name, it will use the catalog data even if the
-   command includes language parameters.  This behavior simplifies loading of
-   old dump files, which are likely to contain out-of-date information
-   about language support functions.
-  </para>
-
-  <para>
-   Ordinarily, the user must have the
-   <productname>PostgreSQL</productname> superuser privilege to
-   register a new language.  However, the owner of a database can register
-   a new language within that database if the language is listed in
-   the <structname>pg_pltemplate</structname> catalog and is marked
-   as allowed to be created by database owners (<structfield>tmpldbacreate</structfield>
-   is true).  The default is that trusted languages can be created
-   by database owners, but this can be adjusted by superusers by modifying
-   the contents of <structname>pg_pltemplate</structname>.
-   The creator of a language becomes its owner and can later
-   drop it, rename it, or assign it to a new owner.
+   The form of <command>CREATE LANGUAGE</command> that does not supply
+   any handler function is obsolete.  For backwards compatibility with
+   old dump files, it is interpreted as <command>CREATE EXTENSION</command>.
+   That will work if the language has been packaged into an extension of
+   the same name, which is the conventional way to set up procedural
+   languages.
   </para>

   <para>
    <command>CREATE OR REPLACE LANGUAGE</command> will either create a
    new language, or replace an existing definition.  If the language
-   already exists, its parameters are updated according to the values
-   specified or taken from <structname>pg_pltemplate</structname>,
+   already exists, its parameters are updated according to the command,
    but the language's ownership and permissions settings do not change,
    and any existing functions written in the language are assumed to still
-   be valid.  In addition to the normal privilege requirements for creating
-   a language, the user must be superuser or owner of the existing language.
-   The <literal>REPLACE</literal> case is mainly meant to be used to
-   ensure that the language exists.  If the language has a
-   <structname>pg_pltemplate</structname> entry then <literal>REPLACE</literal>
-   will not actually change anything about an existing definition, except in
-   the unusual case where the <structname>pg_pltemplate</structname> entry
-   has been modified since the language was created.
+   be valid.
+  </para>
+
+  <para>
+   One must have the
+   <productname>PostgreSQL</productname> superuser privilege to
+   register a new language or change an existing language's parameters.
+   However, once the language is created it is valid to assign ownership of
+   it to a non-superuser, who may then drop it, change its permissions,
+   rename it, or assign it to a new owner.  (Do not, however, assign
+   ownership of the underlying C functions to a non-superuser; that would
+   create a privilege escalation path for that user.)
   </para>
  </refsect1>

@@ -218,12 +182,6 @@ CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="pa
      </listitem>
     </varlistentry>
    </variablelist>
-
-  <para>
-   The <literal>TRUSTED</literal> option and the support function name(s) are
-   ignored if the server has an entry for the specified language
-   name in <structname>pg_pltemplate</structname>.
-  </para>
  </refsect1>

  <refsect1 id="sql-createlanguage-notes">
@@ -255,18 +213,6 @@ CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="pa
   </para>

   <para>
-   The call handler function, the inline handler function (if any),
-   and the validator function (if any)
-   must already exist if the server does not have an entry for the language
-   in <structname>pg_pltemplate</structname>.  But when there is an entry,
-   the functions need not already exist;
-   they will be automatically defined if not present in the database.
-   (This might result in <command>CREATE LANGUAGE</command> failing, if the
-   shared library that implements the language is not available in
-   the installation.)
-  </para>
-
-  <para>
    In <productname>PostgreSQL</productname> versions before 7.3, it was
    necessary to declare handler functions as returning the placeholder
    type <type>opaque</type>, rather than <type>language_handler</type>.
@@ -281,23 +227,20 @@ CREATE [ OR REPLACE ] [ TRUSTED ] [ PROCEDURAL ] LANGUAGE <replaceable class="pa
   <title>Examples</title>

   <para>
-   The preferred way of creating any of the standard procedural languages
-   is just:
-<programlisting>
-CREATE LANGUAGE plperl;
-</programlisting>
-  </para>
-
-  <para>
-   For a language not known in the <structname>pg_pltemplate</structname> catalog, a
-   sequence such as this is needed:
+   A minimal sequence for creating a new procedural language is:
 <programlisting>
 CREATE FUNCTION plsample_call_handler() RETURNS language_handler
     AS '$libdir/plsample'
     LANGUAGE C;
 CREATE LANGUAGE plsample
     HANDLER plsample_call_handler;
-</programlisting></para>
+</programlisting>
+   Typically that would be written in an extension's creation script,
+   and users would do this to install the extension:
+<programlisting>
+CREATE EXTENSION plsample;
+</programlisting>
+  </para>
  </refsect1>

  <refsect1 id="sql-createlanguage-compat">
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index bf66a1c..21e6dd7 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -2279,6 +2279,64 @@ get_available_versions_for_extension(ExtensionControlFile *pcontrol,
 }

 /*
+ * Test whether the given extension exists (not whether it's installed)
+ *
+ * This checks for the existence of a matching control file in the extension
+ * directory.  That's not a bulletproof check, since the file might be
+ * invalid, but this is only used for hints so it doesn't have to be 100%
+ * right.
+ */
+bool
+extension_file_exists(const char *extensionName)
+{
+    bool        result = false;
+    char       *location;
+    DIR           *dir;
+    struct dirent *de;
+
+    location = get_extension_control_directory();
+    dir = AllocateDir(location);
+
+    /*
+     * If the control directory doesn't exist, we want to silently return
+     * false.  Any other error will be reported by ReadDir.
+     */
+    if (dir == NULL && errno == ENOENT)
+    {
+        /* do nothing */
+    }
+    else
+    {
+        while ((de = ReadDir(dir, location)) != NULL)
+        {
+            char       *extname;
+
+            if (!is_extension_control_filename(de->d_name))
+                continue;
+
+            /* extract extension name from 'name.control' filename */
+            extname = pstrdup(de->d_name);
+            *strrchr(extname, '.') = '\0';
+
+            /* ignore it if it's an auxiliary control file */
+            if (strstr(extname, "--"))
+                continue;
+
+            /* done if it matches request */
+            if (strcmp(extname, extensionName) == 0)
+            {
+                result = true;
+                break;
+            }
+        }
+
+        FreeDir(dir);
+    }
+
+    return result;
+}
+
+/*
  * Convert a list of extension names to a name[] Datum
  */
 static Datum
diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 40f1f9a..aa408b8 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -49,6 +49,7 @@
 #include "catalog/pg_type.h"
 #include "commands/alter.h"
 #include "commands/defrem.h"
+#include "commands/extension.h"
 #include "commands/proclang.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -991,7 +992,7 @@ CreateFunction(ParseState *pstate, CreateFunctionStmt *stmt)
         ereport(ERROR,
                 (errcode(ERRCODE_UNDEFINED_OBJECT),
                  errmsg("language \"%s\" does not exist", language),
-                 (PLTemplateExists(language) ?
+                 (extension_file_exists(language) ?
                   errhint("Use CREATE EXTENSION to load the language into the database.") : 0)));

     languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
@@ -2225,7 +2226,7 @@ ExecuteDoStmt(DoStmt *stmt, bool atomic)
         ereport(ERROR,
                 (errcode(ERRCODE_UNDEFINED_OBJECT),
                  errmsg("language \"%s\" does not exist", language),
-                 (PLTemplateExists(language) ?
+                 (extension_file_exists(language) ?
                   errhint("Use CREATE EXTENSION to load the language into the database.") : 0)));

     languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
diff --git a/src/backend/commands/proclang.c b/src/backend/commands/proclang.c
index 343cd1d..520a603 100644
--- a/src/backend/commands/proclang.c
+++ b/src/backend/commands/proclang.c
@@ -13,329 +13,110 @@
  */
 #include "postgres.h"

-#include "access/genam.h"
-#include "access/htup_details.h"
 #include "access/table.h"
 #include "catalog/catalog.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/objectaccess.h"
-#include "catalog/pg_authid.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_namespace.h"
-#include "catalog/pg_pltemplate.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
-#include "commands/dbcommands.h"
 #include "commands/defrem.h"
 #include "commands/proclang.h"
 #include "miscadmin.h"
 #include "parser/parse_func.h"
-#include "parser/parser.h"
-#include "utils/acl.h"
 #include "utils/builtins.h"
-#include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
 #include "utils/syscache.h"


-typedef struct
-{
-    bool        tmpltrusted;    /* trusted? */
-    bool        tmpldbacreate;    /* db owner allowed to create? */
-    char       *tmplhandler;    /* name of handler function */
-    char       *tmplinline;        /* name of anonymous-block handler, or NULL */
-    char       *tmplvalidator;    /* name of validator function, or NULL */
-    char       *tmpllibrary;    /* path of shared library */
-} PLTemplate;
-
-static ObjectAddress create_proc_lang(const char *languageName, bool replace,
-                                      Oid languageOwner, Oid handlerOid, Oid inlineOid,
-                                      Oid valOid, bool trusted);
-static PLTemplate *find_language_template(const char *languageName);
-
 /*
  * CREATE LANGUAGE
  */
 ObjectAddress
 CreateProceduralLanguage(CreatePLangStmt *stmt)
 {
-    PLTemplate *pltemplate;
-    ObjectAddress tmpAddr;
+    const char *languageName = stmt->plname;
+    Oid            languageOwner = GetUserId();
     Oid            handlerOid,
                 inlineOid,
                 valOid;
     Oid            funcrettype;
     Oid            funcargtypes[1];
+    Relation    rel;
+    TupleDesc    tupDesc;
+    Datum        values[Natts_pg_language];
+    bool        nulls[Natts_pg_language];
+    bool        replaces[Natts_pg_language];
+    NameData    langname;
+    HeapTuple    oldtup;
+    HeapTuple    tup;
+    Oid            langoid;
+    bool        is_update;
+    ObjectAddress myself,
+                referenced;

     /*
-     * If we have template information for the language, ignore the supplied
-     * parameters (if any) and use the template information.
+     * Check permission
      */
-    if ((pltemplate = find_language_template(stmt->plname)) != NULL)
-    {
-        List       *funcname;
-
-        /*
-         * Give a notice if we are ignoring supplied parameters.
-         */
-        if (stmt->plhandler)
-            ereport(NOTICE,
-                    (errmsg("using pg_pltemplate information instead of CREATE LANGUAGE parameters")));
-
-        /*
-         * Check permission
-         */
-        if (!superuser())
-        {
-            if (!pltemplate->tmpldbacreate)
-                ereport(ERROR,
-                        (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-                         errmsg("must be superuser to create procedural language \"%s\"",
-                                stmt->plname)));
-            if (!pg_database_ownercheck(MyDatabaseId, GetUserId()))
-                aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_DATABASE,
-                               get_database_name(MyDatabaseId));
-        }
-
-        /*
-         * Find or create the handler function, which we force to be in the
-         * pg_catalog schema.  If already present, it must have the correct
-         * return type.
-         */
-        funcname = SystemFuncName(pltemplate->tmplhandler);
-        handlerOid = LookupFuncName(funcname, 0, funcargtypes, true);
-        if (OidIsValid(handlerOid))
-        {
-            funcrettype = get_func_rettype(handlerOid);
-            if (funcrettype != LANGUAGE_HANDLEROID)
-                ereport(ERROR,
-                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
-                         errmsg("function %s must return type %s",
-                                NameListToString(funcname), "language_handler")));
-        }
-        else
-        {
-            tmpAddr = ProcedureCreate(pltemplate->tmplhandler,
-                                      PG_CATALOG_NAMESPACE,
-                                      false,    /* replace */
-                                      false,    /* returnsSet */
-                                      LANGUAGE_HANDLEROID,
-                                      BOOTSTRAP_SUPERUSERID,
-                                      ClanguageId,
-                                      F_FMGR_C_VALIDATOR,
-                                      pltemplate->tmplhandler,
-                                      pltemplate->tmpllibrary,
-                                      PROKIND_FUNCTION,
-                                      false,    /* security_definer */
-                                      false,    /* isLeakProof */
-                                      false,    /* isStrict */
-                                      PROVOLATILE_VOLATILE,
-                                      PROPARALLEL_UNSAFE,
-                                      buildoidvector(funcargtypes, 0),
-                                      PointerGetDatum(NULL),
-                                      PointerGetDatum(NULL),
-                                      PointerGetDatum(NULL),
-                                      NIL,
-                                      PointerGetDatum(NULL),
-                                      PointerGetDatum(NULL),
-                                      InvalidOid,
-                                      1,
-                                      0);
-            handlerOid = tmpAddr.objectId;
-        }
-
-        /*
-         * Likewise for the anonymous block handler, if required; but we don't
-         * care about its return type.
-         */
-        if (pltemplate->tmplinline)
-        {
-            funcname = SystemFuncName(pltemplate->tmplinline);
-            funcargtypes[0] = INTERNALOID;
-            inlineOid = LookupFuncName(funcname, 1, funcargtypes, true);
-            if (!OidIsValid(inlineOid))
-            {
-                tmpAddr = ProcedureCreate(pltemplate->tmplinline,
-                                          PG_CATALOG_NAMESPACE,
-                                          false,    /* replace */
-                                          false,    /* returnsSet */
-                                          VOIDOID,
-                                          BOOTSTRAP_SUPERUSERID,
-                                          ClanguageId,
-                                          F_FMGR_C_VALIDATOR,
-                                          pltemplate->tmplinline,
-                                          pltemplate->tmpllibrary,
-                                          PROKIND_FUNCTION,
-                                          false,    /* security_definer */
-                                          false,    /* isLeakProof */
-                                          true, /* isStrict */
-                                          PROVOLATILE_VOLATILE,
-                                          PROPARALLEL_UNSAFE,
-                                          buildoidvector(funcargtypes, 1),
-                                          PointerGetDatum(NULL),
-                                          PointerGetDatum(NULL),
-                                          PointerGetDatum(NULL),
-                                          NIL,
-                                          PointerGetDatum(NULL),
-                                          PointerGetDatum(NULL),
-                                          InvalidOid,
-                                          1,
-                                          0);
-                inlineOid = tmpAddr.objectId;
-            }
-        }
-        else
-            inlineOid = InvalidOid;
+    if (!superuser())
+        ereport(ERROR,
+                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+                 errmsg("must be superuser to create custom procedural language")));

+    /*
+     * Lookup the PL handler function and check that it is of the expected
+     * return type
+     */
+    Assert(stmt->plhandler);
+    handlerOid = LookupFuncName(stmt->plhandler, 0, funcargtypes, false);
+    funcrettype = get_func_rettype(handlerOid);
+    if (funcrettype != LANGUAGE_HANDLEROID)
+    {
         /*
-         * Likewise for the validator, if required; but we don't care about
-         * its return type.
+         * We allow OPAQUE just so we can load old dump files.  When we see a
+         * handler function declared OPAQUE, change it to LANGUAGE_HANDLER.
+         * (This is probably obsolete and removable?)
          */
-        if (pltemplate->tmplvalidator)
+        if (funcrettype == OPAQUEOID)
         {
-            funcname = SystemFuncName(pltemplate->tmplvalidator);
-            funcargtypes[0] = OIDOID;
-            valOid = LookupFuncName(funcname, 1, funcargtypes, true);
-            if (!OidIsValid(valOid))
-            {
-                tmpAddr = ProcedureCreate(pltemplate->tmplvalidator,
-                                          PG_CATALOG_NAMESPACE,
-                                          false,    /* replace */
-                                          false,    /* returnsSet */
-                                          VOIDOID,
-                                          BOOTSTRAP_SUPERUSERID,
-                                          ClanguageId,
-                                          F_FMGR_C_VALIDATOR,
-                                          pltemplate->tmplvalidator,
-                                          pltemplate->tmpllibrary,
-                                          PROKIND_FUNCTION,
-                                          false,    /* security_definer */
-                                          false,    /* isLeakProof */
-                                          true, /* isStrict */
-                                          PROVOLATILE_VOLATILE,
-                                          PROPARALLEL_UNSAFE,
-                                          buildoidvector(funcargtypes, 1),
-                                          PointerGetDatum(NULL),
-                                          PointerGetDatum(NULL),
-                                          PointerGetDatum(NULL),
-                                          NIL,
-                                          PointerGetDatum(NULL),
-                                          PointerGetDatum(NULL),
-                                          InvalidOid,
-                                          1,
-                                          0);
-                valOid = tmpAddr.objectId;
-            }
+            ereport(WARNING,
+                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+                     errmsg("changing return type of function %s from %s to %s",
+                            NameListToString(stmt->plhandler),
+                            "opaque", "language_handler")));
+            SetFunctionReturnType(handlerOid, LANGUAGE_HANDLEROID);
         }
         else
-            valOid = InvalidOid;
+            ereport(ERROR,
+                    (errcode(ERRCODE_WRONG_OBJECT_TYPE),
+                     errmsg("function %s must return type %s",
+                            NameListToString(stmt->plhandler), "language_handler")));
+    }

-        /* ok, create it */
-        return create_proc_lang(stmt->plname, stmt->replace, GetUserId(),
-                                handlerOid, inlineOid,
-                                valOid, pltemplate->tmpltrusted);
+    /* validate the inline function */
+    if (stmt->plinline)
+    {
+        funcargtypes[0] = INTERNALOID;
+        inlineOid = LookupFuncName(stmt->plinline, 1, funcargtypes, false);
+        /* return value is ignored, so we don't check the type */
     }
     else
-    {
-        /*
-         * No template, so use the provided information.  If there's no
-         * handler clause, the user is trying to rely on a template that we
-         * don't have, so complain accordingly.
-         */
-        if (!stmt->plhandler)
-            ereport(ERROR,
-                    (errcode(ERRCODE_UNDEFINED_OBJECT),
-                     errmsg("unsupported language \"%s\"",
-                            stmt->plname),
-                     errhint("The supported languages are listed in the pg_pltemplate system catalog.")));
+        inlineOid = InvalidOid;

-        /*
-         * Check permission
-         */
-        if (!superuser())
-            ereport(ERROR,
-                    (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
-                     errmsg("must be superuser to create custom procedural language")));
-
-        /*
-         * Lookup the PL handler function and check that it is of the expected
-         * return type
-         */
-        handlerOid = LookupFuncName(stmt->plhandler, 0, funcargtypes, false);
-        funcrettype = get_func_rettype(handlerOid);
-        if (funcrettype != LANGUAGE_HANDLEROID)
-        {
-            /*
-             * We allow OPAQUE just so we can load old dump files.  When we
-             * see a handler function declared OPAQUE, change it to
-             * LANGUAGE_HANDLER.  (This is probably obsolete and removable?)
-             */
-            if (funcrettype == OPAQUEOID)
-            {
-                ereport(WARNING,
-                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
-                         errmsg("changing return type of function %s from %s to %s",
-                                NameListToString(stmt->plhandler),
-                                "opaque", "language_handler")));
-                SetFunctionReturnType(handlerOid, LANGUAGE_HANDLEROID);
-            }
-            else
-                ereport(ERROR,
-                        (errcode(ERRCODE_WRONG_OBJECT_TYPE),
-                         errmsg("function %s must return type %s",
-                                NameListToString(stmt->plhandler), "language_handler")));
-        }
-
-        /* validate the inline function */
-        if (stmt->plinline)
-        {
-            funcargtypes[0] = INTERNALOID;
-            inlineOid = LookupFuncName(stmt->plinline, 1, funcargtypes, false);
-            /* return value is ignored, so we don't check the type */
-        }
-        else
-            inlineOid = InvalidOid;
-
-        /* validate the validator function */
-        if (stmt->plvalidator)
-        {
-            funcargtypes[0] = OIDOID;
-            valOid = LookupFuncName(stmt->plvalidator, 1, funcargtypes, false);
-            /* return value is ignored, so we don't check the type */
-        }
-        else
-            valOid = InvalidOid;
-
-        /* ok, create it */
-        return create_proc_lang(stmt->plname, stmt->replace, GetUserId(),
-                                handlerOid, inlineOid,
-                                valOid, stmt->pltrusted);
+    /* validate the validator function */
+    if (stmt->plvalidator)
+    {
+        funcargtypes[0] = OIDOID;
+        valOid = LookupFuncName(stmt->plvalidator, 1, funcargtypes, false);
+        /* return value is ignored, so we don't check the type */
     }
-}
-
-/*
- * Guts of language creation.
- */
-static ObjectAddress
-create_proc_lang(const char *languageName, bool replace,
-                 Oid languageOwner, Oid handlerOid, Oid inlineOid,
-                 Oid valOid, bool trusted)
-{
-    Relation    rel;
-    TupleDesc    tupDesc;
-    Datum        values[Natts_pg_language];
-    bool        nulls[Natts_pg_language];
-    bool        replaces[Natts_pg_language];
-    NameData    langname;
-    HeapTuple    oldtup;
-    HeapTuple    tup;
-    Oid            langoid;
-    bool        is_update;
-    ObjectAddress myself,
-                referenced;
+    else
+        valOid = InvalidOid;

+    /* ok to create it */
     rel = table_open(LanguageRelationId, RowExclusiveLock);
     tupDesc = RelationGetDescr(rel);

@@ -348,7 +129,7 @@ create_proc_lang(const char *languageName, bool replace,
     values[Anum_pg_language_lanname - 1] = NameGetDatum(&langname);
     values[Anum_pg_language_lanowner - 1] = ObjectIdGetDatum(languageOwner);
     values[Anum_pg_language_lanispl - 1] = BoolGetDatum(true);
-    values[Anum_pg_language_lanpltrusted - 1] = BoolGetDatum(trusted);
+    values[Anum_pg_language_lanpltrusted - 1] = BoolGetDatum(stmt->pltrusted);
     values[Anum_pg_language_lanplcallfoid - 1] = ObjectIdGetDatum(handlerOid);
     values[Anum_pg_language_laninline - 1] = ObjectIdGetDatum(inlineOid);
     values[Anum_pg_language_lanvalidator - 1] = ObjectIdGetDatum(valOid);
@@ -362,13 +143,17 @@ create_proc_lang(const char *languageName, bool replace,
         Form_pg_language oldform = (Form_pg_language) GETSTRUCT(oldtup);

         /* There is one; okay to replace it? */
-        if (!replace)
+        if (!stmt->replace)
             ereport(ERROR,
                     (errcode(ERRCODE_DUPLICATE_OBJECT),
                      errmsg("language \"%s\" already exists", languageName)));
+
+        /* This is currently pointless, since we already checked superuser */
+#ifdef NOT_USED
         if (!pg_language_ownercheck(oldform->oid, languageOwner))
             aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_LANGUAGE,
                            languageName);
+#endif

         /*
          * Do not change existing oid, ownership or permissions.  Note
@@ -451,83 +236,6 @@ create_proc_lang(const char *languageName, bool replace,
 }

 /*
- * Look to see if we have template information for the given language name.
- */
-static PLTemplate *
-find_language_template(const char *languageName)
-{
-    PLTemplate *result;
-    Relation    rel;
-    SysScanDesc scan;
-    ScanKeyData key;
-    HeapTuple    tup;
-
-    rel = table_open(PLTemplateRelationId, AccessShareLock);
-
-    ScanKeyInit(&key,
-                Anum_pg_pltemplate_tmplname,
-                BTEqualStrategyNumber, F_NAMEEQ,
-                CStringGetDatum(languageName));
-    scan = systable_beginscan(rel, PLTemplateNameIndexId, true,
-                              NULL, 1, &key);
-
-    tup = systable_getnext(scan);
-    if (HeapTupleIsValid(tup))
-    {
-        Form_pg_pltemplate tmpl = (Form_pg_pltemplate) GETSTRUCT(tup);
-        Datum        datum;
-        bool        isnull;
-
-        result = (PLTemplate *) palloc0(sizeof(PLTemplate));
-        result->tmpltrusted = tmpl->tmpltrusted;
-        result->tmpldbacreate = tmpl->tmpldbacreate;
-
-        /* Remaining fields are variable-width so we need heap_getattr */
-        datum = heap_getattr(tup, Anum_pg_pltemplate_tmplhandler,
-                             RelationGetDescr(rel), &isnull);
-        if (!isnull)
-            result->tmplhandler = TextDatumGetCString(datum);
-
-        datum = heap_getattr(tup, Anum_pg_pltemplate_tmplinline,
-                             RelationGetDescr(rel), &isnull);
-        if (!isnull)
-            result->tmplinline = TextDatumGetCString(datum);
-
-        datum = heap_getattr(tup, Anum_pg_pltemplate_tmplvalidator,
-                             RelationGetDescr(rel), &isnull);
-        if (!isnull)
-            result->tmplvalidator = TextDatumGetCString(datum);
-
-        datum = heap_getattr(tup, Anum_pg_pltemplate_tmpllibrary,
-                             RelationGetDescr(rel), &isnull);
-        if (!isnull)
-            result->tmpllibrary = TextDatumGetCString(datum);
-
-        /* Ignore template if handler or library info is missing */
-        if (!result->tmplhandler || !result->tmpllibrary)
-            result = NULL;
-    }
-    else
-        result = NULL;
-
-    systable_endscan(scan);
-
-    table_close(rel, AccessShareLock);
-
-    return result;
-}
-
-
-/*
- * This just returns true if we have a valid template for a given language
- */
-bool
-PLTemplateExists(const char *languageName)
-{
-    return (find_language_template(languageName) != NULL);
-}
-
-/*
  * Guts of language dropping.
  */
 void
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 3f67aaf..9bbc8a6 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -4302,14 +4302,17 @@ NumericOnly_list:    NumericOnly                        { $$ = list_make1($1); }
 CreatePLangStmt:
             CREATE opt_or_replace opt_trusted opt_procedural LANGUAGE NonReservedWord_or_Sconst
             {
-                CreatePLangStmt *n = makeNode(CreatePLangStmt);
-                n->replace = $2;
-                n->plname = $6;
-                /* parameters are all to be supplied by system */
-                n->plhandler = NIL;
-                n->plinline = NIL;
-                n->plvalidator = NIL;
-                n->pltrusted = false;
+                /*
+                 * We now interpret parameterless CREATE LANGUAGE as
+                 * CREATE EXTENSION.  "OR REPLACE" is silently translated
+                 * to "IF NOT EXISTS", which isn't quite the same, but
+                 * seems more useful than throwing an error.  We just
+                 * ignore TRUSTED, as the previous code would have too.
+                 */
+                CreateExtensionStmt *n = makeNode(CreateExtensionStmt);
+                n->if_not_exists = $2;
+                n->extname = $6;
+                n->options = NIL;
                 $$ = (Node *)n;
             }
             | CREATE opt_or_replace opt_trusted opt_procedural LANGUAGE NonReservedWord_or_Sconst
diff --git a/src/include/commands/extension.h b/src/include/commands/extension.h
index 02fc17d..a6a27a6 100644
--- a/src/include/commands/extension.h
+++ b/src/include/commands/extension.h
@@ -47,6 +47,7 @@ extern ObjectAddress ExecAlterExtensionContentsStmt(AlterExtensionContentsStmt *

 extern Oid    get_extension_oid(const char *extname, bool missing_ok);
 extern char *get_extension_name(Oid ext_oid);
+extern bool extension_file_exists(const char *extensionName);

 extern ObjectAddress AlterExtensionNamespace(const char *extensionName, const char *newschema,
                                              Oid *oldschema);
diff --git a/src/include/commands/proclang.h b/src/include/commands/proclang.h
index 9a4bc75..d7b0ab5 100644
--- a/src/include/commands/proclang.h
+++ b/src/include/commands/proclang.h
@@ -1,11 +1,12 @@
-/*
- * src/include/commands/proclang.h
- *
- *-------------------------------------------------------------------------
+/*-------------------------------------------------------------------------
  *
  * proclang.h
  *      prototypes for proclang.c.
  *
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/commands/proclang.h
  *
  *-------------------------------------------------------------------------
  */
@@ -17,7 +18,7 @@

 extern ObjectAddress CreateProceduralLanguage(CreatePLangStmt *stmt);
 extern void DropProceduralLanguageById(Oid langOid);
-extern bool PLTemplateExists(const char *languageName);
+
 extern Oid    get_language_oid(const char *langname, bool missing_ok);

 #endif                            /* PROCLANG_H */
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index a573dfb..03ad677 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -226,11 +226,6 @@
      </row>

      <row>
-      <entry><link linkend="catalog-pg-pltemplate"><structname>pg_pltemplate</structname></link></entry>
-      <entry>template data for procedural languages</entry>
-     </row>
-
-     <row>
       <entry><link linkend="catalog-pg-policy"><structname>pg_policy</structname></link></entry>
       <entry>row-security policies</entry>
      </row>
@@ -4911,113 +4906,6 @@ SCRAM-SHA-256$<replaceable><iteration count></replaceable>:<replaceable>&l
  </sect1>


- <sect1 id="catalog-pg-pltemplate">
-  <title><structname>pg_pltemplate</structname></title>
-
-  <indexterm zone="catalog-pg-pltemplate">
-   <primary>pg_pltemplate</primary>
-  </indexterm>
-
-  <para>
-   The catalog <structname>pg_pltemplate</structname> stores
-   <quote>template</quote> information for procedural languages.
-   A template for a language allows the language to be created in a
-   particular database by a simple <command>CREATE LANGUAGE</command> command,
-   with no need to specify implementation details.
-  </para>
-
-  <para>
-   Unlike most system catalogs, <structname>pg_pltemplate</structname>
-   is shared across all databases of a cluster: there is only one
-   copy of <structname>pg_pltemplate</structname> per cluster, not
-   one per database.  This allows the information to be accessible in
-   each database as it is needed.
-  </para>
-
-  <table>
-   <title><structname>pg_pltemplate</structname> Columns</title>
-
-   <tgroup cols="3">
-    <thead>
-     <row>
-      <entry>Name</entry>
-      <entry>Type</entry>
-      <entry>Description</entry>
-     </row>
-    </thead>
-
-    <tbody>
-     <row>
-      <entry><structfield>tmplname</structfield></entry>
-      <entry><type>name</type></entry>
-      <entry>Name of the language this template is for</entry>
-     </row>
-
-     <row>
-      <entry><structfield>tmpltrusted</structfield></entry>
-      <entry><type>boolean</type></entry>
-      <entry>True if language is considered trusted</entry>
-     </row>
-
-     <row>
-      <entry><structfield>tmpldbacreate</structfield></entry>
-      <entry><type>boolean</type></entry>
-      <entry>True if language may be created by a database owner</entry>
-     </row>
-
-     <row>
-      <entry><structfield>tmplhandler</structfield></entry>
-      <entry><type>text</type></entry>
-      <entry>Name of call handler function</entry>
-     </row>
-
-     <row>
-      <entry><structfield>tmplinline</structfield></entry>
-      <entry><type>text</type></entry>
-      <entry>Name of anonymous-block handler function, or null if none</entry>
-     </row>
-
-     <row>
-      <entry><structfield>tmplvalidator</structfield></entry>
-      <entry><type>text</type></entry>
-      <entry>Name of validator function, or null if none</entry>
-     </row>
-
-     <row>
-      <entry><structfield>tmpllibrary</structfield></entry>
-      <entry><type>text</type></entry>
-      <entry>Path of shared library that implements language</entry>
-     </row>
-
-     <row>
-      <entry><structfield>tmplacl</structfield></entry>
-      <entry><type>aclitem[]</type></entry>
-      <entry>Access privileges for template (not actually used)</entry>
-     </row>
-
-    </tbody>
-   </tgroup>
-  </table>
-
-  <para>
-   There are not currently any commands that manipulate procedural language
-   templates; to change the built-in information, a superuser must modify
-   the table using ordinary <command>INSERT</command>, <command>DELETE</command>,
-   or <command>UPDATE</command> commands.
-  </para>
-
-  <note>
-   <para>
-    It is likely that <structname>pg_pltemplate</structname> will be removed in some
-    future release of <productname>PostgreSQL</productname>, in favor of
-    keeping this knowledge about procedural languages in their respective
-    extension installation scripts.
-   </para>
-  </note>
-
- </sect1>
-
-
  <sect1 id="catalog-pg-policy">
   <title><structname>pg_policy</structname></title>

diff --git a/doc/src/sgml/plpython.sgml b/doc/src/sgml/plpython.sgml
index 4c2f7e8..388a774 100644
--- a/doc/src/sgml/plpython.sgml
+++ b/doc/src/sgml/plpython.sgml
@@ -153,7 +153,7 @@
      <para>
       Daredevils, who want to build a Python-3-only operating system
       environment, can change the contents of
-      <link linkend="catalog-pg-pltemplate"><structname>pg_pltemplate</structname></link>
+      <literal>plpythonu</literal>'s extension control and script files
       to make <literal>plpythonu</literal> be equivalent
       to <literal>plpython3u</literal>, keeping in mind that this
       would make their installation incompatible with most of the rest
diff --git a/src/backend/catalog/Makefile b/src/backend/catalog/Makefile
index a511532..1451b78 100644
--- a/src/backend/catalog/Makefile
+++ b/src/backend/catalog/Makefile
@@ -60,7 +60,7 @@ CATALOG_HEADERS := \
     pg_statistic_ext.h pg_statistic_ext_data.h \
     pg_statistic.h pg_rewrite.h pg_trigger.h pg_event_trigger.h pg_description.h \
     pg_cast.h pg_enum.h pg_namespace.h pg_conversion.h pg_depend.h \
-    pg_database.h pg_db_role_setting.h pg_tablespace.h pg_pltemplate.h \
+    pg_database.h pg_db_role_setting.h pg_tablespace.h \
     pg_authid.h pg_auth_members.h pg_shdepend.h pg_shdescription.h \
     pg_ts_config.h pg_ts_config_map.h pg_ts_dict.h \
     pg_ts_parser.h pg_ts_template.h pg_extension.h \
@@ -86,7 +86,7 @@ POSTGRES_BKI_DATA = $(addprefix $(top_srcdir)/src/include/catalog/,\
     pg_cast.dat pg_class.dat pg_collation.dat pg_conversion.dat \
     pg_database.dat pg_language.dat \
     pg_namespace.dat pg_opclass.dat pg_operator.dat pg_opfamily.dat \
-    pg_pltemplate.dat pg_proc.dat pg_range.dat pg_tablespace.dat \
+    pg_proc.dat pg_range.dat pg_tablespace.dat \
     pg_ts_config.dat pg_ts_config_map.dat pg_ts_dict.dat pg_ts_parser.dat \
     pg_ts_template.dat pg_type.dat \
     )
diff --git a/src/backend/catalog/catalog.c b/src/backend/catalog/catalog.c
index 1af31c2..8d424de 100644
--- a/src/backend/catalog/catalog.c
+++ b/src/backend/catalog/catalog.c
@@ -32,7 +32,6 @@
 #include "catalog/pg_authid.h"
 #include "catalog/pg_database.h"
 #include "catalog/pg_namespace.h"
-#include "catalog/pg_pltemplate.h"
 #include "catalog/pg_db_role_setting.h"
 #include "catalog/pg_replication_origin.h"
 #include "catalog/pg_shdepend.h"
@@ -243,7 +242,6 @@ IsSharedRelation(Oid relationId)
     if (relationId == AuthIdRelationId ||
         relationId == AuthMemRelationId ||
         relationId == DatabaseRelationId ||
-        relationId == PLTemplateRelationId ||
         relationId == SharedDescriptionRelationId ||
         relationId == SharedDependRelationId ||
         relationId == SharedSecLabelRelationId ||
@@ -259,7 +257,6 @@ IsSharedRelation(Oid relationId)
         relationId == AuthMemMemRoleIndexId ||
         relationId == DatabaseNameIndexId ||
         relationId == DatabaseOidIndexId ||
-        relationId == PLTemplateNameIndexId ||
         relationId == SharedDescriptionObjIndexId ||
         relationId == SharedDependDependerIndexId ||
         relationId == SharedDependReferenceIndexId ||
@@ -279,8 +276,6 @@ IsSharedRelation(Oid relationId)
         relationId == PgDatabaseToastIndex ||
         relationId == PgDbRoleSettingToastTable ||
         relationId == PgDbRoleSettingToastIndex ||
-        relationId == PgPlTemplateToastTable ||
-        relationId == PgPlTemplateToastIndex ||
         relationId == PgReplicationOriginToastTable ||
         relationId == PgReplicationOriginToastIndex ||
         relationId == PgShdescriptionToastTable ||
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index bf69adc..6b0fd42 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -11396,9 +11396,9 @@ dumpProcLang(Archive *fout, ProcLangInfo *plang)
     }

     /*
-     * If the functions are dumpable then emit a traditional CREATE LANGUAGE
-     * with parameters.  Otherwise, we'll write a parameterless command, which
-     * will rely on data from pg_pltemplate.
+     * If the functions are dumpable then emit a complete CREATE LANGUAGE with
+     * parameters.  Otherwise, we'll write a parameterless command, which will
+     * be interpreted as CREATE EXTENSION.
      */
     useParams = (funcInfo != NULL &&
                  (inlineInfo != NULL || !OidIsValid(plang->laninline)) &&
@@ -11431,11 +11431,11 @@ dumpProcLang(Archive *fout, ProcLangInfo *plang)
         /*
          * If not dumping parameters, then use CREATE OR REPLACE so that the
          * command will not fail if the language is preinstalled in the target
-         * database.  We restrict the use of REPLACE to this case so as to
-         * eliminate the risk of replacing a language with incompatible
-         * parameter settings: this command will only succeed at all if there
-         * is a pg_pltemplate entry, and if there is one, the existing entry
-         * must match it too.
+         * database.
+         *
+         * Modern servers will interpret this as CREATE EXTENSION IF NOT
+         * EXISTS; perhaps we should emit that instead?  But it might just add
+         * confusion.
          */
         appendPQExpBuffer(defqry, "CREATE OR REPLACE PROCEDURAL LANGUAGE %s",
                           qlanname);
diff --git a/src/bin/pg_upgrade/function.c b/src/bin/pg_upgrade/function.c
index ac984db..a239c53 100644
--- a/src/bin/pg_upgrade/function.c
+++ b/src/bin/pg_upgrade/function.c
@@ -214,13 +214,9 @@ check_loadable_libraries(void)
              * plpython2u language was created with library name plpython2.so
              * as a symbolic link to plpython.so.  In Postgres 9.1, only the
              * plpython2.so library was created, and both plpythonu and
-             * plpython2u pointing to it.  For this reason, any reference to
+             * plpython2u point to it.  For this reason, any reference to
              * library name "plpython" in an old PG <= 9.1 cluster must look
              * for "plpython2" in the new cluster.
-             *
-             * For this case, we could check pg_pltemplate, but that only
-             * works for languages, and does not help with function shared
-             * objects, so we just do a general fix.
              */
             if (GET_MAJOR_VERSION(old_cluster.major_version) < 901 &&
                 strcmp(lib, "$libdir/plpython") == 0)
diff --git a/src/include/catalog/indexing.h b/src/include/catalog/indexing.h
index ef4445b..7294d59 100644
--- a/src/include/catalog/indexing.h
+++ b/src/include/catalog/indexing.h
@@ -206,9 +206,6 @@ DECLARE_UNIQUE_INDEX(pg_opfamily_am_name_nsp_index, 2754, on pg_opfamily using b
 DECLARE_UNIQUE_INDEX(pg_opfamily_oid_index, 2755, on pg_opfamily using btree(oid oid_ops));
 #define OpfamilyOidIndexId    2755

-DECLARE_UNIQUE_INDEX(pg_pltemplate_name_index, 1137, on pg_pltemplate using btree(tmplname name_ops));
-#define PLTemplateNameIndexId  1137
-
 DECLARE_UNIQUE_INDEX(pg_proc_oid_index, 2690, on pg_proc using btree(oid oid_ops));
 #define ProcedureOidIndexId  2690
 DECLARE_UNIQUE_INDEX(pg_proc_proname_args_nsp_index, 2691, on pg_proc using btree(proname name_ops, proargtypes
oidvector_ops,pronamespace oid_ops)); 
diff --git a/src/include/catalog/pg_pltemplate.dat b/src/include/catalog/pg_pltemplate.dat
deleted file mode 100644
index 6f6d167..0000000
--- a/src/include/catalog/pg_pltemplate.dat
+++ /dev/null
@@ -1,51 +0,0 @@
-#----------------------------------------------------------------------
-#
-# pg_pltemplate.dat
-#    Initial contents of the pg_pltemplate system catalog.
-#
-# Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
-# Portions Copyright (c) 1994, Regents of the University of California
-#
-# src/include/catalog/pg_pltemplate.dat
-#
-#----------------------------------------------------------------------
-
-[
-
-{ tmplname => 'plpgsql', tmpltrusted => 't', tmpldbacreate => 't',
-  tmplhandler => 'plpgsql_call_handler', tmplinline => 'plpgsql_inline_handler',
-  tmplvalidator => 'plpgsql_validator', tmpllibrary => '$libdir/plpgsql',
-  tmplacl => '_null_' },
-{ tmplname => 'pltcl', tmpltrusted => 't', tmpldbacreate => 't',
-  tmplhandler => 'pltcl_call_handler', tmplinline => '_null_',
-  tmplvalidator => '_null_', tmpllibrary => '$libdir/pltcl',
-  tmplacl => '_null_' },
-{ tmplname => 'pltclu', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'pltclu_call_handler', tmplinline => '_null_',
-  tmplvalidator => '_null_', tmpllibrary => '$libdir/pltcl',
-  tmplacl => '_null_' },
-{ tmplname => 'plperl', tmpltrusted => 't', tmpldbacreate => 't',
-  tmplhandler => 'plperl_call_handler', tmplinline => 'plperl_inline_handler',
-  tmplvalidator => 'plperl_validator', tmpllibrary => '$libdir/plperl',
-  tmplacl => '_null_' },
-{ tmplname => 'plperlu', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plperlu_call_handler', tmplinline => 'plperlu_inline_handler',
-  tmplvalidator => 'plperlu_validator', tmpllibrary => '$libdir/plperl',
-  tmplacl => '_null_' },
-{ tmplname => 'plpythonu', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plpython_call_handler',
-  tmplinline => 'plpython_inline_handler',
-  tmplvalidator => 'plpython_validator', tmpllibrary => '$libdir/plpython2',
-  tmplacl => '_null_' },
-{ tmplname => 'plpython2u', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plpython2_call_handler',
-  tmplinline => 'plpython2_inline_handler',
-  tmplvalidator => 'plpython2_validator', tmpllibrary => '$libdir/plpython2',
-  tmplacl => '_null_' },
-{ tmplname => 'plpython3u', tmpltrusted => 'f', tmpldbacreate => 'f',
-  tmplhandler => 'plpython3_call_handler',
-  tmplinline => 'plpython3_inline_handler',
-  tmplvalidator => 'plpython3_validator', tmpllibrary => '$libdir/plpython3',
-  tmplacl => '_null_' },
-
-]
diff --git a/src/include/catalog/pg_pltemplate.h b/src/include/catalog/pg_pltemplate.h
deleted file mode 100644
index ce89000..0000000
--- a/src/include/catalog/pg_pltemplate.h
+++ /dev/null
@@ -1,52 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * pg_pltemplate.h
- *      definition of the "PL template" system catalog (pg_pltemplate)
- *
- *
- * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * src/include/catalog/pg_pltemplate.h
- *
- * NOTES
- *      The Catalog.pm module reads this file and derives schema
- *      information.
- *
- *-------------------------------------------------------------------------
- */
-#ifndef PG_PLTEMPLATE_H
-#define PG_PLTEMPLATE_H
-
-#include "catalog/genbki.h"
-#include "catalog/pg_pltemplate_d.h"
-
-/* ----------------
- *        pg_pltemplate definition.  cpp turns this into
- *        typedef struct FormData_pg_pltemplate
- * ----------------
- */
-CATALOG(pg_pltemplate,1136,PLTemplateRelationId) BKI_SHARED_RELATION
-{
-    NameData    tmplname;        /* name of PL */
-    bool        tmpltrusted;    /* PL is trusted? */
-    bool        tmpldbacreate;    /* PL is installable by db owner? */
-
-#ifdef CATALOG_VARLEN            /* variable-length fields start here */
-    text        tmplhandler BKI_FORCE_NOT_NULL; /* name of call handler
-                                                 * function */
-    text        tmplinline;        /* name of anonymous-block handler, or NULL */
-    text        tmplvalidator;    /* name of validator function, or NULL */
-    text        tmpllibrary BKI_FORCE_NOT_NULL; /* path of shared library */
-    aclitem        tmplacl[1];        /* access privileges for template */
-#endif
-} FormData_pg_pltemplate;
-
-/* ----------------
- *        Form_pg_pltemplate corresponds to a pointer to a row with
- *        the format of pg_pltemplate relation.
- * ----------------
- */
-typedef FormData_pg_pltemplate *Form_pg_pltemplate;
-
-#endif                            /* PG_PLTEMPLATE_H */
diff --git a/src/include/catalog/toasting.h b/src/include/catalog/toasting.h
index cc5dfed..5a047fc 100644
--- a/src/include/catalog/toasting.h
+++ b/src/include/catalog/toasting.h
@@ -86,9 +86,6 @@ DECLARE_TOAST(pg_database, 4177, 4178);
 DECLARE_TOAST(pg_db_role_setting, 2966, 2967);
 #define PgDbRoleSettingToastTable 2966
 #define PgDbRoleSettingToastIndex 2967
-DECLARE_TOAST(pg_pltemplate, 4179, 4180);
-#define PgPlTemplateToastTable 4179
-#define PgPlTemplateToastIndex 4180
 DECLARE_TOAST(pg_replication_origin, 4181, 4182);
 #define PgReplicationOriginToastTable 4181
 #define PgReplicationOriginToastIndex 4182
diff --git a/src/pl/plpython/plpy_main.c b/src/pl/plpython/plpy_main.c
index 6edfcf2..0d9564e 100644
--- a/src/pl/plpython/plpy_main.c
+++ b/src/pl/plpython/plpy_main.c
@@ -33,7 +33,7 @@
  */

 #if PY_MAJOR_VERSION >= 3
-/* Use separate names to avoid clash in pg_pltemplate */
+/* Use separate names to reduce confusion */
 #define plpython_validator plpython3_validator
 #define plpython_call_handler plpython3_call_handler
 #define plpython_inline_handler plpython3_inline_handler
diff --git a/src/test/regress/expected/sanity_check.out b/src/test/regress/expected/sanity_check.out
index 070de78..f0cd40b 100644
--- a/src/test/regress/expected/sanity_check.out
+++ b/src/test/regress/expected/sanity_check.out
@@ -134,7 +134,6 @@ pg_opclass|t
 pg_operator|t
 pg_opfamily|t
 pg_partitioned_table|t
-pg_pltemplate|t
 pg_policy|t
 pg_proc|t
 pg_publication|t

pgsql-hackers by date:

Previous
From: Pavel Stehule
Date:
Subject: proposal: minscale, rtrim, btrim functions for numeric
Next
From: Mark Dilger
Date:
Subject: Re: Using multiple extended statistics for estimates