Support SET FROM CURRENT in CREATE/ALTER FUNCTION, ALTER DATABASE, ALTER ROLE.

(Actually, it works as a plain statement too, but I didn't document that
because it seems a bit useless.)  Unify VariableResetStmt with
VariableSetStmt, and clean up some ancient cruft in the representation of
same.

doc/src/sgml/ref/alter_database.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_database.sgml,v 1.19 2006/09/16 00:30:16 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_database.sgml,v 1.20 2007/09/03 18:46:29 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -26,12 +26,14 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
 
     CONNECTION LIMIT <replaceable class="PARAMETER">connlimit</replaceable>
 
-ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> SET <replaceable>parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
-ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>parameter</replaceable>
-
 ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> RENAME TO <replaceable>newname</replaceable>
 
 ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> OWNER TO <replaceable>new_owner</replaceable>
+
+ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
+ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> SET <replaceable>configuration_parameter</replaceable> FROM CURRENT
+ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>configuration_parameter</replaceable>
+ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> RESET ALL
 </synopsis>
  </refsynopsisdiv>
 
@@ -49,7 +51,24 @@ ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> OWNER TO <repla
   </para> 
 
   <para>
-   The second and third forms change the session default for a run-time
+   The second form changes the name of the database.  Only the database
+   owner or a superuser can rename a database; non-superuser owners must
+   also have the
+   <literal>CREATEDB</literal> privilege.  The current database cannot
+   be renamed.  (Connect to a different database if you need to do
+   that.)
+  </para>
+
+  <para>
+   The third form changes the owner of the database.
+   To alter the owner, you must own the database and also be a direct or
+   indirect member of the new owning role, and you must have the
+   <literal>CREATEDB</literal> privilege.
+   (Note that superusers have all these privileges automatically.)
+  </para>
+
+  <para>
+   The remaining forms change the session default for a run-time
    configuration variable for a <productname>PostgreSQL</productname>
    database. Whenever a new session is subsequently started in that
    database, the specified value becomes the session default value.
@@ -60,23 +79,6 @@ ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> OWNER TO <repla
    database.  Certain variables cannot be set this way, or can only be
    set by a superuser.
   </para>
-
-  <para>
-   The fourth form changes the name of the database.  Only the database
-   owner or a superuser can rename a database; non-superuser owners must
-   also have the
-   <literal>CREATEDB</literal> privilege.  The current database cannot
-   be renamed.  (Connect to a different database if you need to do
-   that.)
-  </para>
-
-  <para>
-   The fifth form changes the owner of the database.
-   To alter the owner, you must own the database and also be a direct or
-   indirect member of the new owning role, and you must have the
-   <literal>CREATEDB</literal> privilege.
-   (Note that superusers have all these privileges automatically.)
-  </para>
  </refsect1>
 
  <refsect1>
@@ -102,28 +104,6 @@ ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> OWNER TO <repla
       </listitem>
      </varlistentry> 
 
-     <varlistentry>
-      <term><replaceable>parameter</replaceable></term>
-      <term><replaceable>value</replaceable></term>
-      <listitem>
-       <para>
-        Set this database's session default for the specified configuration
-        parameter to the given value.  If
-        <replaceable>value</replaceable> is <literal>DEFAULT</literal>
-        or, equivalently, <literal>RESET</literal> is used, the
-        database-specific setting is removed, so the system-wide default
-        setting will be inherited in new sessions.  Use <literal>RESET
-        ALL</literal> to clear all database-specific settings.
-       </para>
-
-       <para>
-        See <xref linkend="sql-set" endterm="sql-set-title"> and <xref linkend="runtime-config">
-        for more information about allowed parameter names
-        and values.
-       </para>
-      </listitem>
-     </varlistentry>
-
    <varlistentry>
     <term><replaceable>newname</replaceable></term>
     <listitem>
@@ -141,6 +121,30 @@ ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> OWNER TO <repla
      </para>
     </listitem>
    </varlistentry>
+
+     <varlistentry>
+      <term><replaceable>configuration_parameter</replaceable></term>
+      <term><replaceable>value</replaceable></term>
+      <listitem>
+       <para>
+        Set this database's session default for the specified configuration
+        parameter to the given value.  If
+        <replaceable>value</replaceable> is <literal>DEFAULT</literal>
+        or, equivalently, <literal>RESET</literal> is used, the
+        database-specific setting is removed, so the system-wide default
+        setting will be inherited in new sessions.  Use <literal>RESET
+        ALL</literal> to clear all database-specific settings.
+        <literal>SET FROM CURRENT</> saves the session's current value of
+        the parameter as the database-specific value.
+       </para>
+
+       <para>
+        See <xref linkend="sql-set" endterm="sql-set-title"> and <xref linkend="runtime-config">
+        for more information about allowed parameter names
+        and values.
+       </para>
+      </listitem>
+     </varlistentry>
   </variablelist>
  </refsect1>
 
@@ -148,10 +152,10 @@ ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> OWNER TO <repla
   <title>Notes</title>
 
   <para>
-   It is also possible to tie a session default to a specific user
+   It is also possible to tie a session default to a specific role
    rather than to a database; see
-   <xref linkend="sql-alteruser" endterm="sql-alteruser-title">.
+   <xref linkend="sql-alterrole" endterm="sql-alterrole-title">.
-   User-specific settings override database-specific
+   Role-specific settings override database-specific
    ones if there is a conflict.
   </para>
  </refsect1>

doc/src/sgml/ref/alter_function.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_function.sgml,v 1.14 2007/09/03 00:39:12 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_function.sgml,v 1.15 2007/09/03 18:46:29 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -21,7 +21,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
-    <replaceable class="PARAMETER">action</replaceable> [, ... ] [ RESTRICT ]
+    <replaceable class="PARAMETER">action</replaceable> [ ... ] [ RESTRICT ]
 ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
     RENAME TO <replaceable>new_name</replaceable>
 ALTER FUNCTION <replaceable>name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] )
@@ -36,8 +36,10 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
     [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
     COST <replaceable class="parameter">execution_cost</replaceable>
     ROWS <replaceable class="parameter">result_rows</replaceable>
-    SET <replaceable class="parameter">parameter</replaceable> { TO | = } { <replaceable class="parameter">value</replaceable> | DEFAULT }
+    SET <replaceable class="parameter">configuration_parameter</replaceable> { TO | = } { <replaceable class="parameter">value</replaceable> | DEFAULT }
-    RESET <replaceable class="parameter">parameter</replaceable>
+    SET <replaceable class="parameter">configuration_parameter</replaceable> FROM CURRENT
+    RESET <replaceable class="parameter">configuration_parameter</replaceable>
+    RESET ALL
 </synopsis>
  </refsynopsisdiv>
   
@@ -215,7 +217,7 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
    </varlistentry>
 
      <varlistentry>
-      <term><replaceable>parameter</replaceable></term>
+      <term><replaceable>configuration_parameter</replaceable></term>
       <term><replaceable>value</replaceable></term>
       <listitem>
        <para>
@@ -226,6 +228,8 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
         setting is removed, so that the function executes with the value
         present in its environment.  Use <literal>RESET
         ALL</literal> to clear all function-local settings.
+        <literal>SET FROM CURRENT</> saves the session's current value of
+        the parameter as the value to be applied when the function is entered.
        </para>
 
        <para>

doc/src/sgml/ref/alter_role.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_role.sgml,v 1.8 2007/05/15 19:43:51 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_role.sgml,v 1.9 2007/09/03 18:46:29 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -37,7 +37,9 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
 ALTER ROLE <replaceable class="PARAMETER">name</replaceable> RENAME TO <replaceable>newname</replaceable>
 
 ALTER ROLE <replaceable class="PARAMETER">name</replaceable> SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
+ALTER ROLE <replaceable class="PARAMETER">name</replaceable> SET <replaceable>configuration_parameter</replaceable> FROM CURRENT
 ALTER ROLE <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>configuration_parameter</replaceable>
+ALTER ROLE <replaceable class="PARAMETER">name</replaceable> RESET ALL
 </synopsis>
  </refsynopsisdiv>
 
@@ -77,7 +79,7 @@ ALTER ROLE <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>
   </para>
 
   <para>
-   The third and the fourth variant change a role's session default for
+   The remaining variants change a role's session default for
    a specified configuration variable.  Whenever the role subsequently
    starts a new session, the specified value becomes the session default,
    overriding whatever setting is present in <filename>postgresql.conf</>
@@ -155,6 +157,8 @@ ALTER ROLE <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>
         role-specific variable setting is removed, so the role will
         inherit the system-wide default setting in new sessions.  Use
         <literal>RESET ALL</literal> to clear all role-specific settings.
+        <literal>SET FROM CURRENT</> saves the session's current value of
+        the parameter as the role-specific value.
        </para>
 
        <para>

doc/src/sgml/ref/alter_user.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_user.sgml,v 1.43 2007/05/15 19:43:51 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_user.sgml,v 1.44 2007/09/03 18:46:29 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -37,7 +37,9 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
 ALTER USER <replaceable class="PARAMETER">name</replaceable> RENAME TO <replaceable>newname</replaceable>
 
 ALTER USER <replaceable class="PARAMETER">name</replaceable> SET <replaceable>configuration_parameter</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
+ALTER USER <replaceable class="PARAMETER">name</replaceable> SET <replaceable>configuration_parameter</replaceable> FROM CURRENT
 ALTER USER <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>configuration_parameter</replaceable>
+ALTER USER <replaceable class="PARAMETER">name</replaceable> RESET ALL
 </synopsis>
  </refsynopsisdiv>
 

doc/src/sgml/ref/create_function.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.76 2007/09/03 00:39:13 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_function.sgml,v 1.77 2007/09/03 18:46:29 tgl Exp $
 -->
 
 <refentry id="SQL-CREATEFUNCTION">
@@ -28,7 +28,7 @@ CREATE [ OR REPLACE ] FUNCTION
     | [ EXTERNAL ] SECURITY INVOKER | [ EXTERNAL ] SECURITY DEFINER
     | COST <replaceable class="parameter">execution_cost</replaceable>
     | ROWS <replaceable class="parameter">result_rows</replaceable>
-    | SET <replaceable class="parameter">parameter</replaceable> { TO | = } { <replaceable class="parameter">value</replaceable> | DEFAULT }
+    | SET <replaceable class="parameter">configuration_parameter</replaceable> { TO <replaceable class="parameter">value</replaceable> | = <replaceable class="parameter">value</replaceable> | FROM CURRENT }
     | AS '<replaceable class="parameter">definition</replaceable>'
     | AS '<replaceable class="parameter">obj_file</replaceable>', '<replaceable class="parameter">link_symbol</replaceable>'
   } ...
@@ -324,13 +324,15 @@ CREATE [ OR REPLACE ] FUNCTION
     </varlistentry>
 
     <varlistentry>
-     <term><replaceable>parameter</replaceable></term>
+     <term><replaceable>configuration_parameter</replaceable></term>
      <term><replaceable>value</replaceable></term>
      <listitem>
       <para>
        The <literal>SET</> clause causes the specified configuration
        parameter to be set to the specified value when the function is
        entered, and then restored to its prior value when the function exits.
+       <literal>SET FROM CURRENT</> saves the session's current value of
+       the parameter as the value to be applied when the function is entered.
       </para>
 
       <para>

src/backend/commands/dbcommands.c

@@ -13,7 +13,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.197 2007/08/01 22:45:08 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.198 2007/09/03 18:46:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -886,7 +886,7 @@ AlterDatabaseSet(AlterDatabaseSetStmt *stmt)
 	char		repl_null[Natts_pg_database];
 	char		repl_repl[Natts_pg_database];
 
-	valuestr = flatten_set_variable_args(stmt->variable, stmt->value);
+	valuestr = ExtractSetVariableArgs(stmt->setstmt);
 
 	/*
 	 * Get the old tuple.  We don't need a lock on the database per se,
@@ -910,12 +910,12 @@ AlterDatabaseSet(AlterDatabaseSetStmt *stmt)
 		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_DATABASE,
 					   stmt->dbname);
 
-	MemSet(repl_repl, ' ', sizeof(repl_repl));
+	memset(repl_repl, ' ', sizeof(repl_repl));
 	repl_repl[Anum_pg_database_datconfig - 1] = 'r';
 
-	if (strcmp(stmt->variable, "all") == 0 && valuestr == NULL)
+	if (stmt->setstmt->kind == VAR_RESET_ALL)
 	{
-		/* RESET ALL */
+		/* RESET ALL, so just set datconfig to null */
 		repl_null[Anum_pg_database_datconfig - 1] = 'n';
 		repl_val[Anum_pg_database_datconfig - 1] = (Datum) 0;
 	}
@@ -927,15 +927,16 @@ AlterDatabaseSet(AlterDatabaseSetStmt *stmt)
 
 		repl_null[Anum_pg_database_datconfig - 1] = ' ';
 
+		/* Extract old value of datconfig */
 		datum = heap_getattr(tuple, Anum_pg_database_datconfig,
 							 RelationGetDescr(rel), &isnull);
-
 		a = isnull ? NULL : DatumGetArrayTypeP(datum);
 
+		/* Update (valuestr is NULL in RESET cases) */
 		if (valuestr)
-			a = GUCArrayAdd(a, stmt->variable, valuestr);
+			a = GUCArrayAdd(a, stmt->setstmt->name, valuestr);
 		else
-			a = GUCArrayDelete(a, stmt->variable);
+			a = GUCArrayDelete(a, stmt->setstmt->name);
 
 		if (a)
 			repl_val[Anum_pg_database_datconfig - 1] = PointerGetDatum(a);
@@ -943,7 +944,8 @@ AlterDatabaseSet(AlterDatabaseSetStmt *stmt)
 			repl_null[Anum_pg_database_datconfig - 1] = 'n';
 	}
 
-	newtuple = heap_modifytuple(tuple, RelationGetDescr(rel), repl_val, repl_null, repl_repl);
+	newtuple = heap_modifytuple(tuple, RelationGetDescr(rel),
+								repl_val, repl_null, repl_repl);
 	simple_heap_update(rel, &tuple->t_self, newtuple);
 
 	/* Update indexes */

src/backend/commands/functioncmds.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.84 2007/09/03 00:39:15 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.85 2007/09/03 18:46:29 tgl Exp $
  *
  * DESCRIPTION
  *	  These routines take the parse tree and pick out the
@@ -354,7 +354,7 @@ interpret_func_volatility(DefElem *defel)
 }
 
 /*
- * Update a proconfig value according to a list of SET and RESET items.
+ * Update a proconfig value according to a list of VariableSetStmt items.
  *
  * The input and result may be NULL to signify a null entry.
  */
@@ -365,33 +365,20 @@ update_proconfig_value(ArrayType *a, List *set_items)
 
 	foreach(l, set_items)
 	{
-		Node   *sitem = (Node *) lfirst(l);
+		VariableSetStmt *sstmt = (VariableSetStmt *) lfirst(l);
 
-		if (IsA(sitem, VariableSetStmt))
+		Assert(IsA(sstmt, VariableSetStmt));
+		if (sstmt->kind == VAR_RESET_ALL)
+			a = NULL;
+		else
 		{
-			VariableSetStmt *sstmt = (VariableSetStmt *) sitem;
+			char	   *valuestr = ExtractSetVariableArgs(sstmt);
 
-			if (sstmt->args)
+			if (valuestr)
-			{
-				char	   *valuestr;
-
-				valuestr = flatten_set_variable_args(sstmt->name, sstmt->args);
 				a = GUCArrayAdd(a, sstmt->name, valuestr);
-			}
+			else				/* RESET */
-			else				/* SET TO DEFAULT */
 				a = GUCArrayDelete(a, sstmt->name);
 		}
-		else if (IsA(sitem, VariableResetStmt))
-		{
-			VariableResetStmt *rstmt = (VariableResetStmt *) sitem;
-
-			if (strcmp(rstmt->name, "all") == 0)
-				a = NULL;	/* RESET ALL */
-			else
-				a = GUCArrayDelete(a, rstmt->name);
-		}
-		else
-			elog(ERROR, "unexpected node type: %d", nodeTag(sitem));
 	}
 
 	return a;

src/backend/commands/user.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.176 2007/02/01 19:10:26 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.177 2007/09/03 18:46:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -721,9 +721,8 @@ AlterRoleSet(AlterRoleSetStmt *stmt)
 	Datum		repl_val[Natts_pg_authid];
 	char		repl_null[Natts_pg_authid];
 	char		repl_repl[Natts_pg_authid];
-	int			i;
 
-	valuestr = flatten_set_variable_args(stmt->variable, stmt->value);
+	valuestr = ExtractSetVariableArgs(stmt->setstmt);
 
 	rel = heap_open(AuthIdRelationId, RowExclusiveLock);
 	oldtuple = SearchSysCache(AUTHNAME,
@@ -754,14 +753,14 @@ AlterRoleSet(AlterRoleSetStmt *stmt)
 					 errmsg("permission denied")));
 	}
 
-	for (i = 0; i < Natts_pg_authid; i++)
+	memset(repl_repl, ' ', sizeof(repl_repl));
-		repl_repl[i] = ' ';
-
 	repl_repl[Anum_pg_authid_rolconfig - 1] = 'r';
-	if (strcmp(stmt->variable, "all") == 0 && valuestr == NULL)
+
+	if (stmt->setstmt->kind == VAR_RESET_ALL)
 	{
-		/* RESET ALL */
+		/* RESET ALL, so just set rolconfig to null */
 		repl_null[Anum_pg_authid_rolconfig - 1] = 'n';
+		repl_val[Anum_pg_authid_rolconfig - 1] = (Datum) 0;
 	}
 	else
 	{
@@ -771,15 +770,16 @@ AlterRoleSet(AlterRoleSetStmt *stmt)
 
 		repl_null[Anum_pg_authid_rolconfig - 1] = ' ';
 
+		/* Extract old value of rolconfig */
 		datum = SysCacheGetAttr(AUTHNAME, oldtuple,
 								Anum_pg_authid_rolconfig, &isnull);
-
 		array = isnull ? NULL : DatumGetArrayTypeP(datum);
 
+		/* Update (valuestr is NULL in RESET cases) */
 		if (valuestr)
-			array = GUCArrayAdd(array, stmt->variable, valuestr);
+			array = GUCArrayAdd(array, stmt->setstmt->name, valuestr);
 		else
-			array = GUCArrayDelete(array, stmt->variable);
+			array = GUCArrayDelete(array, stmt->setstmt->name);
 
 		if (array)
 			repl_val[Anum_pg_authid_rolconfig - 1] = PointerGetDatum(array);

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.381 2007/08/31 01:44:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.382 2007/09/03 18:46:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2525,8 +2525,7 @@ _copyAlterDatabaseSetStmt(AlterDatabaseSetStmt *from)
 	AlterDatabaseSetStmt *newnode = makeNode(AlterDatabaseSetStmt);
 
 	COPY_STRING_FIELD(dbname);
-	COPY_STRING_FIELD(variable);
+	COPY_NODE_FIELD(setstmt);
-	COPY_NODE_FIELD(value);
 
 	return newnode;
 }
@@ -2597,6 +2596,7 @@ _copyVariableSetStmt(VariableSetStmt *from)
 {
 	VariableSetStmt *newnode = makeNode(VariableSetStmt);
 
+	COPY_SCALAR_FIELD(kind);
 	COPY_STRING_FIELD(name);
 	COPY_NODE_FIELD(args);
 	COPY_SCALAR_FIELD(is_local);
@@ -2614,16 +2614,6 @@ _copyVariableShowStmt(VariableShowStmt *from)
 	return newnode;
 }
 
-static VariableResetStmt *
-_copyVariableResetStmt(VariableResetStmt *from)
-{
-	VariableResetStmt *newnode = makeNode(VariableResetStmt);
-
-	COPY_STRING_FIELD(name);
-
-	return newnode;
-}
-
 static DiscardStmt *
 _copyDiscardStmt(DiscardStmt *from)
 {
@@ -2746,8 +2736,7 @@ _copyAlterRoleSetStmt(AlterRoleSetStmt *from)
 	AlterRoleSetStmt *newnode = makeNode(AlterRoleSetStmt);
 
 	COPY_STRING_FIELD(role);
-	COPY_STRING_FIELD(variable);
+	COPY_NODE_FIELD(setstmt);
-	COPY_NODE_FIELD(value);
 
 	return newnode;
 }
@@ -3428,9 +3417,6 @@ copyObject(void *from)
 		case T_VariableShowStmt:
 			retval = _copyVariableShowStmt(from);
 			break;
-		case T_VariableResetStmt:
-			retval = _copyVariableResetStmt(from);
-			break;
 		case T_DiscardStmt:
 			retval = _copyDiscardStmt(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.312 2007/08/31 01:44:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.313 2007/09/03 18:46:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1325,8 +1325,7 @@ static bool
 _equalAlterDatabaseSetStmt(AlterDatabaseSetStmt *a, AlterDatabaseSetStmt *b)
 {
 	COMPARE_STRING_FIELD(dbname);
-	COMPARE_STRING_FIELD(variable);
+	COMPARE_NODE_FIELD(setstmt);
-	COMPARE_NODE_FIELD(value);
 
 	return true;
 }
@@ -1385,6 +1384,7 @@ _equalAlterSeqStmt(AlterSeqStmt *a, AlterSeqStmt *b)
 static bool
 _equalVariableSetStmt(VariableSetStmt *a, VariableSetStmt *b)
 {
+	COMPARE_SCALAR_FIELD(kind);
 	COMPARE_STRING_FIELD(name);
 	COMPARE_NODE_FIELD(args);
 	COMPARE_SCALAR_FIELD(is_local);
@@ -1400,14 +1400,6 @@ _equalVariableShowStmt(VariableShowStmt *a, VariableShowStmt *b)
 	return true;
 }
 
-static bool
-_equalVariableResetStmt(VariableResetStmt *a, VariableResetStmt *b)
-{
-	COMPARE_STRING_FIELD(name);
-
-	return true;
-}
-
 static bool
 _equalDiscardStmt(DiscardStmt *a, DiscardStmt *b)
 {
@@ -1511,8 +1503,7 @@ static bool
 _equalAlterRoleSetStmt(AlterRoleSetStmt *a, AlterRoleSetStmt *b)
 {
 	COMPARE_STRING_FIELD(role);
-	COMPARE_STRING_FIELD(variable);
+	COMPARE_NODE_FIELD(setstmt);
-	COMPARE_NODE_FIELD(value);
 
 	return true;
 }
@@ -2356,9 +2347,6 @@ equal(void *a, void *b)
 		case T_VariableShowStmt:
 			retval = _equalVariableShowStmt(a, b);
 			break;
-		case T_VariableResetStmt:
-			retval = _equalVariableResetStmt(a, b);
-			break;
 		case T_DiscardStmt:
 			retval = _equalDiscardStmt(a, b);
 			break;

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.601 2007/09/03 00:39:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.602 2007/09/03 18:46:30 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -292,7 +292,7 @@ static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args)
 
 %type <istmt>	insert_rest
 
-%type <vsetstmt> set_rest
+%type <vsetstmt> set_rest SetResetClause
 
 %type <node>	TableElement ConstraintElem TableFuncElement
 %type <node>	columnDef
@@ -330,7 +330,7 @@ static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args)
 %type <ival>	Iconst SignedIconst
 %type <str>		Sconst comment_text
 %type <str>		RoleId opt_granted_by opt_boolean ColId_or_Sconst
-%type <list>	var_list var_list_or_default
+%type <list>	var_list
 %type <str>		ColId ColLabel var_name type_function_name param_name
 %type <node>	var_value zone_value
 
@@ -796,20 +796,11 @@ AlterRoleStmt:
 		;
 
 AlterRoleSetStmt:
-			ALTER ROLE RoleId SET set_rest
+			ALTER ROLE RoleId SetResetClause
 				{
 					AlterRoleSetStmt *n = makeNode(AlterRoleSetStmt);
 					n->role = $3;
-					n->variable = $5->name;
+					n->setstmt = $4;
-					n->value = $5->args;
-					$$ = (Node *)n;
-				}
-			| ALTER ROLE RoleId VariableResetStmt
-				{
-					AlterRoleSetStmt *n = makeNode(AlterRoleSetStmt);
-					n->role = $3;
-					n->variable = ((VariableResetStmt *)$4)->name;
-					n->value = NIL;
 					$$ = (Node *)n;
 				}
 		;
@@ -834,20 +825,11 @@ AlterUserStmt:
 
 
 AlterUserSetStmt:
-			ALTER USER RoleId SET set_rest
+			ALTER USER RoleId SetResetClause
 				{
 					AlterRoleSetStmt *n = makeNode(AlterRoleSetStmt);
 					n->role = $3;
-					n->variable = $5->name;
+					n->setstmt = $4;
-					n->value = $5->args;
-					$$ = (Node *)n;
-				}
-			| ALTER USER RoleId VariableResetStmt
-				{
-					AlterRoleSetStmt *n = makeNode(AlterRoleSetStmt);
-					n->role = $3;
-					n->variable = ((VariableResetStmt *)$4)->name;
-					n->value = NIL;
 					$$ = (Node *)n;
 				}
 			;
@@ -1056,31 +1038,60 @@ VariableSetStmt:
 				}
 		;
 
-set_rest:  var_name TO var_list_or_default
+set_rest:	/* Generic SET syntaxes: */
+			var_name TO var_list
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_VALUE;
 					n->name = $1;
 					n->args = $3;
 					$$ = n;
 				}
-			| var_name '=' var_list_or_default
+			| var_name '=' var_list
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_VALUE;
 					n->name = $1;
 					n->args = $3;
 					$$ = n;
 				}
+			| var_name TO DEFAULT
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_DEFAULT;
+					n->name = $1;
+					$$ = n;
+				}
+			| var_name '=' DEFAULT
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_DEFAULT;
+					n->name = $1;
+					$$ = n;
+				}
+			| var_name FROM CURRENT_P
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_CURRENT;
+					n->name = $1;
+					$$ = n;
+				}
+			/* Special syntaxes mandated by SQL standard: */
 			| TIME ZONE zone_value
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_VALUE;
 					n->name = "timezone";
 					if ($3 != NULL)
 						n->args = list_make1($3);
+					else
+						n->kind = VAR_SET_DEFAULT;
 					$$ = n;
 				}
 			| TRANSACTION transaction_mode_list
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_MULTI;
 					n->name = "TRANSACTION";
 					n->args = $2;
 					$$ = n;
@@ -1088,6 +1099,7 @@ set_rest:  var_name TO var_list_or_default
 			| SESSION CHARACTERISTICS AS TRANSACTION transaction_mode_list
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_MULTI;
 					n->name = "SESSION CHARACTERISTICS";
 					n->args = $5;
 					$$ = n;
@@ -1095,14 +1107,18 @@ set_rest:  var_name TO var_list_or_default
 			| NAMES opt_encoding
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_VALUE;
 					n->name = "client_encoding";
 					if ($2 != NULL)
 						n->args = list_make1(makeStringConst($2, NULL));
+					else
+						n->kind = VAR_SET_DEFAULT;
 					$$ = n;
 				}
 			| ROLE ColId_or_Sconst
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_VALUE;
 					n->name = "role";
 					n->args = list_make1(makeStringConst($2, NULL));
 					$$ = n;
@@ -1110,6 +1126,7 @@ set_rest:  var_name TO var_list_or_default
 			| SESSION AUTHORIZATION ColId_or_Sconst
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_VALUE;
 					n->name = "session_authorization";
 					n->args = list_make1(makeStringConst($3, NULL));
 					$$ = n;
@@ -1117,37 +1134,28 @@ set_rest:  var_name TO var_list_or_default
 			| SESSION AUTHORIZATION DEFAULT
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_DEFAULT;
 					n->name = "session_authorization";
-					n->args = NIL;
 					$$ = n;
 				}
 			| XML_P OPTION document_or_content
 				{
 					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_SET_VALUE;
 					n->name = "xmloption";
 					n->args = list_make1(makeStringConst($3 == XMLOPTION_DOCUMENT ? "DOCUMENT" : "CONTENT", NULL));
 					$$ = n;
 				}
 		;
 
-var_name:
+var_name:	ColId								{ $$ = $1; }
-			ColId								{ $$ = $1; }
 			| var_name '.' ColId
 				{
-					int qLen = strlen($1);
+					$$ = palloc(strlen($1) + strlen($3) + 2);
-					char* qualName = palloc(qLen + strlen($3) + 2);
+					sprintf($$, "%s.%s", $1, $3);
-					strcpy(qualName, $1);
-					qualName[qLen] = '.';
-					strcpy(qualName + qLen + 1, $3);
-					$$ = qualName;
 				}
 		;
 
-var_list_or_default:
-			var_list								{ $$ = $1; }
-			| DEFAULT								{ $$ = NIL; }
-		;
-
 var_list:	var_value								{ $$ = list_make1($1); }
 			| var_list ',' var_value				{ $$ = lappend($1, $3); }
 		;
@@ -1231,6 +1239,49 @@ ColId_or_Sconst:
 			| SCONST								{ $$ = $1; }
 		;
 
+VariableResetStmt:
+			RESET var_name
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_RESET;
+					n->name = $2;
+					$$ = (Node *) n;
+				}
+			| RESET TIME ZONE
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_RESET;
+					n->name = "timezone";
+					$$ = (Node *) n;
+				}
+			| RESET TRANSACTION ISOLATION LEVEL
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_RESET;
+					n->name = "transaction_isolation";
+					$$ = (Node *) n;
+				}
+			| RESET SESSION AUTHORIZATION
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_RESET;
+					n->name = "session_authorization";
+					$$ = (Node *) n;
+				}
+			| RESET ALL
+				{
+					VariableSetStmt *n = makeNode(VariableSetStmt);
+					n->kind = VAR_RESET_ALL;
+					$$ = (Node *) n;
+				}
+		;
+
+/* SetResetClause allows SET or RESET without LOCAL */
+SetResetClause:
+			SET set_rest					{ $$ = $2; }
+			| VariableResetStmt				{ $$ = (VariableSetStmt *) $1; }
+		;
+
 
 VariableShowStmt:
 			SHOW var_name
@@ -1265,39 +1316,6 @@ VariableShowStmt:
 				}
 		;
 
-VariableResetStmt:
-			RESET var_name
-				{
-					VariableResetStmt *n = makeNode(VariableResetStmt);
-					n->name = $2;
-					$$ = (Node *) n;
-				}
-			| RESET TIME ZONE
-				{
-					VariableResetStmt *n = makeNode(VariableResetStmt);
-					n->name = "timezone";
-					$$ = (Node *) n;
-				}
-			| RESET TRANSACTION ISOLATION LEVEL
-				{
-					VariableResetStmt *n = makeNode(VariableResetStmt);
-					n->name = "transaction_isolation";
-					$$ = (Node *) n;
-				}
-			| RESET SESSION AUTHORIZATION
-				{
-					VariableResetStmt *n = makeNode(VariableResetStmt);
-					n->name = "session_authorization";
-					$$ = (Node *) n;
-				}
-			| RESET ALL
-				{
-					VariableResetStmt *n = makeNode(VariableResetStmt);
-					n->name = "all";
-					$$ = (Node *) n;
-				}
-		;
-
 
 ConstraintsSetStmt:
 			SET CONSTRAINTS constraints_set_list constraints_set_mode
@@ -4270,15 +4288,10 @@ common_func_opt_item:
 				{
 					$$ = makeDefElem("rows", (Node *)$2);
 				}
-			| SET set_rest
+			| SetResetClause
 				{
 					/* we abuse the normal content of a DefElem here */
-					$$ = makeDefElem("set", (Node *)$2);
+					$$ = makeDefElem("set", (Node *)$1);
-				}
-			| VariableResetStmt
-				{
-					/* we abuse the normal content of a DefElem here */
-					$$ = makeDefElem("set", $1);
 				}
 		;
 
@@ -5391,20 +5404,11 @@ AlterDatabaseStmt:
 		;
 
 AlterDatabaseSetStmt:
-			ALTER DATABASE database_name SET set_rest
+			ALTER DATABASE database_name SetResetClause
 				{
 					AlterDatabaseSetStmt *n = makeNode(AlterDatabaseSetStmt);
 					n->dbname = $3;
-					n->variable = $5->name;
+					n->setstmt = $4;
-					n->value = $5->args;
-					$$ = (Node *)n;
-				}
-			| ALTER DATABASE database_name VariableResetStmt
-				{
-					AlterDatabaseSetStmt *n = makeNode(AlterDatabaseSetStmt);
-					n->dbname = $3;
-					n->variable = ((VariableResetStmt *)$4)->name;
-					n->value = NIL;
 					$$ = (Node *)n;
 				}
 		;

src/backend/tcop/pquery.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.116 2007/04/27 22:05:49 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.117 2007/09/03 18:46:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1159,7 +1159,6 @@ PortalRunUtility(Portal portal, Node *utilityStmt, bool isTopLevel,
 		  IsA(utilityStmt, LockStmt) ||
 		  IsA(utilityStmt, VariableSetStmt) ||
 		  IsA(utilityStmt, VariableShowStmt) ||
-		  IsA(utilityStmt, VariableResetStmt) ||
 		  IsA(utilityStmt, ConstraintsSetStmt) ||
 	/* efficiency hacks from here down */
 		  IsA(utilityStmt, FetchStmt) ||

src/backend/tcop/utility.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.285 2007/08/21 01:11:17 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.286 2007/09/03 18:46:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1041,48 +1041,7 @@ ProcessUtility(Node *parsetree,
 			break;
 
 		case T_VariableSetStmt:
-			{
+			ExecSetVariableStmt((VariableSetStmt *) parsetree);
-				VariableSetStmt *n = (VariableSetStmt *) parsetree;
-
-				/*
-				 * Special cases for special SQL syntax that effectively sets
-				 * more than one variable per statement.
-				 */
-				if (strcmp(n->name, "TRANSACTION") == 0)
-				{
-					ListCell   *head;
-
-					foreach(head, n->args)
-					{
-						DefElem    *item = (DefElem *) lfirst(head);
-
-						if (strcmp(item->defname, "transaction_isolation") == 0)
-							SetPGVariable("transaction_isolation",
-										  list_make1(item->arg), n->is_local);
-						else if (strcmp(item->defname, "transaction_read_only") == 0)
-							SetPGVariable("transaction_read_only",
-										  list_make1(item->arg), n->is_local);
-					}
-				}
-				else if (strcmp(n->name, "SESSION CHARACTERISTICS") == 0)
-				{
-					ListCell   *head;
-
-					foreach(head, n->args)
-					{
-						DefElem    *item = (DefElem *) lfirst(head);
-
-						if (strcmp(item->defname, "transaction_isolation") == 0)
-							SetPGVariable("default_transaction_isolation",
-										  list_make1(item->arg), n->is_local);
-						else if (strcmp(item->defname, "transaction_read_only") == 0)
-							SetPGVariable("default_transaction_read_only",
-										  list_make1(item->arg), n->is_local);
-					}
-				}
-				else
-					SetPGVariable(n->name, n->args, n->is_local);
-			}
 			break;
 
 		case T_VariableShowStmt:
@@ -1093,14 +1052,6 @@ ProcessUtility(Node *parsetree,
 			}
 			break;
 
-		case T_VariableResetStmt:
-			{
-				VariableResetStmt *n = (VariableResetStmt *) parsetree;
-
-				ResetPGVariable(n->name, isTopLevel);
-			}
-			break;
-
 		case T_DiscardStmt:
 			DiscardCommand((DiscardStmt *) parsetree, isTopLevel);
 			break;
@@ -1924,19 +1875,30 @@ CreateCommandTag(Node *parsetree)
 			break;
 
 		case T_VariableSetStmt:
-			tag = "SET";
+			switch (((VariableSetStmt *) parsetree)->kind)
+			{
+				case VAR_SET_VALUE:
+				case VAR_SET_CURRENT:
+				case VAR_SET_DEFAULT:
+				case VAR_SET_MULTI:
+					tag = "SET";
+					break;
+				case VAR_RESET:
+				case VAR_RESET_ALL:
+					tag = "RESET";
+					break;
+				default:
+					tag = "???";
+			}
 			break;
 
 		case T_VariableShowStmt:
 			tag = "SHOW";
 			break;
 
-		case T_VariableResetStmt:
-			tag = "RESET";
-			break;
-
 		case T_DiscardStmt:
-			switch (((DiscardStmt *) parsetree)->target) {
+			switch (((DiscardStmt *) parsetree)->target)
+			{
 				case DISCARD_ALL:
 					tag = "DISCARD ALL";
 					break;
@@ -2402,10 +2364,6 @@ GetCommandLogLevel(Node *parsetree)
 			lev = LOGSTMT_ALL;
 			break;
 
-		case T_VariableResetStmt:
-			lev = LOGSTMT_ALL;
-			break;
-
 		case T_CreateTrigStmt:
 			lev = LOGSTMT_DDL;
 			break;

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.415 2007/09/03 00:39:19 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.416 2007/09/03 18:46:30 tgl Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -4870,10 +4870,10 @@ IsSuperuserConfigOption(const char *name)
  * We need to be told the name of the variable the args are for, because
  * the flattening rules vary (ugh).
  *
- * The result is NULL if input is NIL (ie, SET ... TO DEFAULT), otherwise
+ * The result is NULL if args is NIL (ie, SET ... TO DEFAULT), otherwise
  * a palloc'd string.
  */
-char *
+static char *
 flatten_set_variable_args(const char *name, List *args)
 {
 	struct config_generic *record;
@@ -4881,10 +4881,7 @@ flatten_set_variable_args(const char *name, List *args)
 	StringInfoData buf;
 	ListCell   *l;
 
-	/*
+	/* Fast path if just DEFAULT */
-	 * Fast path if just DEFAULT.  We do not check the variable name in this
-	 * case --- necessary for RESET ALL to work correctly.
-	 */
 	if (args == NIL)
 		return NULL;
 
@@ -4979,6 +4976,108 @@ flatten_set_variable_args(const char *name, List *args)
  * SET command
  */
 void
+ExecSetVariableStmt(VariableSetStmt *stmt)
+{
+	switch (stmt->kind)
+	{
+		case VAR_SET_VALUE:
+		case VAR_SET_CURRENT:
+			set_config_option(stmt->name,
+							  ExtractSetVariableArgs(stmt),
+							  (superuser() ? PGC_SUSET : PGC_USERSET),
+							  PGC_S_SESSION,
+							  stmt->is_local,
+							  true);
+			break;
+		case VAR_SET_MULTI:
+			/*
+			 * Special case for special SQL syntax that effectively sets
+			 * more than one variable per statement.
+			 */
+			if (strcmp(stmt->name, "TRANSACTION") == 0)
+			{
+				ListCell   *head;
+
+				foreach(head, stmt->args)
+				{
+					DefElem    *item = (DefElem *) lfirst(head);
+
+					if (strcmp(item->defname, "transaction_isolation") == 0)
+						SetPGVariable("transaction_isolation",
+									  list_make1(item->arg), stmt->is_local);
+					else if (strcmp(item->defname, "transaction_read_only") == 0)
+						SetPGVariable("transaction_read_only",
+									  list_make1(item->arg), stmt->is_local);
+					else
+						elog(ERROR, "unexpected SET TRANSACTION element: %s",
+							 item->defname);
+				}
+			}
+			else if (strcmp(stmt->name, "SESSION CHARACTERISTICS") == 0)
+			{
+				ListCell   *head;
+
+				foreach(head, stmt->args)
+				{
+					DefElem    *item = (DefElem *) lfirst(head);
+
+					if (strcmp(item->defname, "transaction_isolation") == 0)
+						SetPGVariable("default_transaction_isolation",
+									  list_make1(item->arg), stmt->is_local);
+					else if (strcmp(item->defname, "transaction_read_only") == 0)
+						SetPGVariable("default_transaction_read_only",
+									  list_make1(item->arg), stmt->is_local);
+					else
+						elog(ERROR, "unexpected SET SESSION element: %s",
+							 item->defname);
+				}
+			}
+			else
+				elog(ERROR, "unexpected SET MULTI element: %s",
+					 stmt->name);
+			break;
+		case VAR_SET_DEFAULT:
+		case VAR_RESET:
+			set_config_option(stmt->name,
+							  NULL,
+							  (superuser() ? PGC_SUSET : PGC_USERSET),
+							  PGC_S_SESSION,
+							  stmt->is_local,
+							  true);
+			break;
+		case VAR_RESET_ALL:
+			ResetAllOptions();
+			break;
+	}
+}
+
+/*
+ * Get the value to assign for a VariableSetStmt, or NULL if it's RESET.
+ * The result is palloc'd.
+ *
+ * This is exported for use by actions such as ALTER ROLE SET.
+ */
+char *
+ExtractSetVariableArgs(VariableSetStmt *stmt)
+{
+	switch (stmt->kind)
+	{
+		case VAR_SET_VALUE:
+			return flatten_set_variable_args(stmt->name, stmt->args);
+		case VAR_SET_CURRENT:
+			return GetConfigOptionByName(stmt->name, NULL);
+		default:
+			return NULL;
+	}
+}
+
+/*
+ * SetPGVariable - SET command exported as an easily-C-callable function.
+ *
+ * This provides access to SET TO value, as well as SET TO DEFAULT (expressed
+ * by passing args == NIL), but not SET FROM CURRENT functionality.
+ */
+void
 SetPGVariable(const char *name, List *args, bool is_local)
 {
 	char	   *argstring = flatten_set_variable_args(name, args);
@@ -5045,6 +5144,7 @@ set_config_by_name(PG_FUNCTION_ARGS)
 	PG_RETURN_TEXT_P(result_text);
 }
 
+
 static void
 define_custom_variable(struct config_generic * variable)
 {
@@ -5283,23 +5383,6 @@ GetPGVariableResultDesc(const char *name)
 	return tupdesc;
 }
 
-/*
- * RESET command
- */
-void
-ResetPGVariable(const char *name, bool isTopLevel)
-{
-	if (pg_strcasecmp(name, "all") == 0)
-		ResetAllOptions();
-	else
-		set_config_option(name,
-						  NULL,
-						  (superuser() ? PGC_SUSET : PGC_USERSET),
-						  PGC_S_SESSION,
-						  false,
-						  true);
-}
-
 
 /*
  * SHOW command

src/include/nodes/nodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.203 2007/08/21 01:11:27 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.204 2007/09/03 18:46:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -275,7 +275,6 @@ typedef enum NodeTag
 	T_AlterSeqStmt,
 	T_VariableSetStmt,
 	T_VariableShowStmt,
-	T_VariableResetStmt,
 	T_DiscardStmt,
 	T_CreateTrigStmt,
 	T_DropPropertyStmt,

src/include/nodes/parsenodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.352 2007/08/22 05:13:50 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.353 2007/09/03 18:46:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1050,6 +1050,42 @@ typedef struct CopyStmt
 	List	   *options;		/* List of DefElem nodes */
 } CopyStmt;
 
+/* ----------------------
+ * SET Statement (includes RESET)
+ *
+ * "SET var TO DEFAULT" and "RESET var" are semantically equivalent, but we
+ * preserve the distinction in VariableSetKind for CreateCommandTag().
+ * ----------------------
+ */
+typedef enum
+{
+	VAR_SET_VALUE,				/* SET var = value */
+	VAR_SET_DEFAULT,			/* SET var TO DEFAULT */
+	VAR_SET_CURRENT,			/* SET var FROM CURRENT */
+	VAR_SET_MULTI,				/* special case for SET TRANSACTION ... */
+	VAR_RESET,					/* RESET var */
+	VAR_RESET_ALL				/* RESET ALL */
+} VariableSetKind;
+
+typedef struct VariableSetStmt
+{
+	NodeTag		type;
+	VariableSetKind kind;
+	char	   *name;			/* variable to be set */
+	List	   *args;			/* List of A_Const nodes */
+	bool		is_local;		/* SET LOCAL? */
+} VariableSetStmt;
+
+/* ----------------------
+ * Show Statement
+ * ----------------------
+ */
+typedef struct VariableShowStmt
+{
+	NodeTag		type;
+	char	   *name;
+} VariableShowStmt;
+
 /* ----------------------
  *		Create Table Statement
  *
@@ -1264,8 +1300,7 @@ typedef struct AlterRoleSetStmt
 {
 	NodeTag		type;
 	char	   *role;			/* role name */
-	char	   *variable;		/* GUC variable name */
+	VariableSetStmt *setstmt;	/* SET or RESET subcommand */
-	List	   *value;			/* value for variable, or NIL for Reset */
 } AlterRoleSetStmt;
 
 typedef struct DropRoleStmt
@@ -1781,9 +1816,8 @@ typedef struct AlterDatabaseStmt
 typedef struct AlterDatabaseSetStmt
 {
 	NodeTag		type;
-	char	   *dbname;
+	char	   *dbname;			/* database name */
-	char	   *variable;
+	VariableSetStmt *setstmt;	/* SET or RESET subcommand */
-	List	   *value;
 } AlterDatabaseSetStmt;
 
 /* ----------------------
@@ -1848,41 +1882,6 @@ typedef struct CheckPointStmt
 	NodeTag		type;
 } CheckPointStmt;
 
-/* ----------------------
- * Set Statement
- * ----------------------
- */
-
-typedef struct VariableSetStmt
-{
-	NodeTag		type;
-	char	   *name;
-	List	   *args;
-	bool		is_local;		/* SET LOCAL */
-} VariableSetStmt;
-
-/* ----------------------
- * Show Statement
- * ----------------------
- */
-
-typedef struct VariableShowStmt
-{
-	NodeTag		type;
-	char	   *name;
-} VariableShowStmt;
-
-/* ----------------------
- * Reset Statement
- * ----------------------
- */
-
-typedef struct VariableResetStmt
-{
-	NodeTag		type;
-	char	   *name;
-} VariableResetStmt;
-
 /* ----------------------
  * Discard Statement
  * ----------------------

src/include/utils/guc.h

@@ -7,12 +7,13 @@
  * Copyright (c) 2000-2007, PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
- * $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.84 2007/09/03 00:39:25 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.85 2007/09/03 18:46:30 tgl Exp $
  *--------------------------------------------------------------------
  */
 #ifndef GUC_H
 #define GUC_H
 
+#include "nodes/parsenodes.h"
 #include "tcop/dest.h"
 #include "utils/array.h"
 
@@ -203,9 +204,9 @@ extern int	GetNumConfigOptions(void);
 extern void SetPGVariable(const char *name, List *args, bool is_local);
 extern void GetPGVariable(const char *name, DestReceiver *dest);
 extern TupleDesc GetPGVariableResultDesc(const char *name);
-extern void ResetPGVariable(const char *name, bool isTopLevel);
 
-extern char *flatten_set_variable_args(const char *name, List *args);
+extern void ExecSetVariableStmt(VariableSetStmt *stmt);
+extern char *ExtractSetVariableArgs(VariableSetStmt *stmt);
 
 extern void ProcessGUCArray(ArrayType *array,
 						GucContext context, GucSource source, bool isLocal);