OK, here's the final version of ALTER TABLE ... SET WITHOUT CLUSTER.

Has docs + regression test.

Christopher Kings-Lynne

doc/src/sgml/ref/alter_table.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.70 2004/05/27 03:30:11 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.71 2004/06/02 21:01:08 momjian Exp $
 PostgreSQL documentation
 -->
 
@@ -42,6 +42,7 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
     SET WITHOUT OIDS
     OWNER TO <replaceable class="PARAMETER">new_owner</replaceable>
     CLUSTER ON <replaceable class="PARAMETER">index_name</replaceable>
+    SET WITHOUT CLUSTER
 </synopsis>
  </refsynopsisdiv>
 
@@ -213,12 +214,24 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
     <term><literal>CLUSTER</literal></term>
     <listitem>
      <para>
-      This form selects the default controlling index for future <xref linkend="SQL-CLUSTER" endterm="sql-cluster-title">
+      This form selects the default index for future 
+      <xref linkend="SQL-CLUSTER" endterm="sql-cluster-title">
       operations.
      </para>
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>SET WITHOUT CLUSTER</literal></term>
+    <listitem>
+     <para>
+      This form removes the most recently used
+      <xref linkend="SQL-CLUSTER" endterm="sql-cluster-title">
+      index specification from the table.
+     </para>
+    </listitem>
+   </varlistentry>
+ 
    <varlistentry>
     <term><literal>RENAME</literal></term>
     <listitem>

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.108 2004/05/26 04:41:12 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.109 2004/06/02 21:01:08 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -233,6 +233,7 @@ static void ATPostAlterTypeCleanup(List **wqueue, AlteredTableInfo *tab);
 static void ATPostAlterTypeParse(char *cmd, List **wqueue);
 static void ATExecChangeOwner(Oid relationOid, int32 newOwnerSysId);
 static void ATExecClusterOn(Relation rel, const char *indexName);
+static void ATExecDropCluster(Relation rel);
 static int	ri_trigger_type(Oid tgfoid);
 static void update_ri_trigger_args(Oid relid,
 					   const char *oldname,
@@ -1922,8 +1923,9 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			pass = AT_PASS_MISC;
 			break;
 		case AT_ClusterOn:	/* CLUSTER ON */
+		case AT_DropCluster:	/* SET WITHOUT CLUSTER */
 			ATSimplePermissions(rel, false);
-			/* This command never recurses */
+			/* These commands never recurse */
 			/* No command-specific prep needed */
 			pass = AT_PASS_MISC;
 			break;
@@ -2083,6 +2085,9 @@ ATExecCmd(AlteredTableInfo *tab, Relation rel, AlterTableCmd *cmd)
 		case AT_ClusterOn:		/* CLUSTER ON */
 			ATExecClusterOn(rel, cmd->name);
 			break;
+		case AT_DropCluster:		/* SET WITHOUT CLUSTER */
+			ATExecDropCluster(rel);
+			break;
 		case AT_DropOids:		/* SET WITHOUT OIDS */
 			/*
 			 * Nothing to do here; we'll have generated a DropColumn subcommand
@@ -5044,6 +5049,19 @@ ATExecClusterOn(Relation rel, const char *indexName)
 	mark_index_clustered(rel, indexOid);
 }
 
+/*
+ * ALTER TABLE SET WITHOUT CLUSTER
+ *
+ * We have to find any indexes on the table that have indisclustered bit
+ * set and turn it off.
+ */
+static void
+ATExecDropCluster(Relation rel)
+{
+	mark_index_clustered(rel, InvalidOid);
+}
+
+
 /*
  * ALTER TABLE CREATE TOAST TABLE
  *

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.459 2004/06/01 03:28:48 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.460 2004/06/02 21:01:09 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -1277,6 +1277,14 @@ alter_table_cmd:
 					n->name = $3;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> SET WITHOUT CLUSTER */ 
+			| SET WITHOUT CLUSTER
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropCluster;
+					n->name = NULL;
+					$$ = (Node *)n;
+				}
 		;
 
 alter_column_default:

src/include/nodes/parsenodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.256 2004/05/26 13:57:02 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.257 2004/06/02 21:01:09 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -793,6 +793,7 @@ typedef enum AlterTableType
 	AT_ToastTable,				/* create toast table */
 	AT_ChangeOwner,				/* change owner */
 	AT_ClusterOn,				/* CLUSTER ON */
+	AT_DropCluster,				/* SET WITHOUT CLUSTER */
 	AT_DropOids					/* SET WITHOUT OIDS */
 } AlterTableType;
 

src/test/regress/expected/cluster.out

@@ -297,6 +297,17 @@ WHERE pg_class.oid=indexrelid
  clstr_tst_b_c
 (1 row)
 
+-- Try turning off all clustering
+ALTER TABLE clstr_tst SET WITHOUT CLUSTER;
+SELECT pg_class.relname FROM pg_index, pg_class, pg_class AS pg_class_2
+WHERE pg_class.oid=indexrelid
+	AND indrelid=pg_class_2.oid
+	AND pg_class_2.relname = 'clstr_tst'
+ 	AND indisclustered;
+  relname 
+ ---------
+ (0 rows)
+
 -- Verify that clustering all tables does in fact cluster the right ones
 CREATE USER clstr_user;
 CREATE TABLE clstr_1 (a INT PRIMARY KEY);

src/test/regress/sql/cluster.sql

@@ -95,6 +95,14 @@ WHERE pg_class.oid=indexrelid
 	AND pg_class_2.relname = 'clstr_tst'
 	AND indisclustered;
 
+-- Try turning off all clustering
+ALTER TABLE clstr_tst SET WITHOUT CLUSTER;
+SELECT pg_class.relname FROM pg_index, pg_class, pg_class AS pg_class_2
+WHERE pg_class.oid=indexrelid
+	AND indrelid=pg_class_2.oid
+	AND pg_class_2.relname = 'clstr_tst'
+	AND indisclustered;
+
 -- Verify that clustering all tables does in fact cluster the right ones
 CREATE USER clstr_user;
 CREATE TABLE clstr_1 (a INT PRIMARY KEY);