Add ALTER TABLE <tablename> CLUSTER ON <indexname>

Alvaro Herrera

doc/src/sgml/ref/alter_table.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.56 2003/02/19 04:06:28 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.57 2003/03/20 18:52:47 momjian Exp $
 PostgreSQL documentation
 -->
 
@@ -46,6 +46,8 @@ ALTER TABLE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ * ]
     DROP CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> [ RESTRICT | CASCADE ]
 ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
     OWNER TO <replaceable class="PARAMETER">new_owner</replaceable> 
+ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
+	CLUSTER ON <replaceable class="PARAMETER">index_name</replaceable>
   </synopsis>
 
   <refsect2 id="R2-SQL-ALTERTABLE-1">
@@ -138,6 +140,15 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><replaceable class="PARAMETER"> index_name </replaceable></term>
+      <listitem>
+       <para>
+	The index name on which the table should be marked for clustering.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term>CASCADE</term>
       <listitem>
@@ -344,6 +355,16 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term>CLUSTER</term>
+    <listitem>
+     <para>
+      This form marks a table for future <xref linkend="SQL-CLUSTER" endterm="sql-cluster-title">
+      operations.
+     </para>
+    </listitem>
+   </varlistentry>
+
   </variablelist>
 
   <para>

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.68 2003/03/20 03:34:55 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.69 2003/03/20 18:52:47 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3795,6 +3795,90 @@ CheckTupleType(Form_pg_class tuple_class)
 	}
 }
 
+/*
+ * ALTER TABLE CLUSTER ON
+ *
+ * The only thing we have to do is to change the indisclustered bits.
+ */
+void
+AlterTableClusterOn(Oid relOid, const char *indexName)
+{
+	Relation 		rel,
+					pg_index;
+	List		   *index;
+	Oid		 		indexOid;
+	HeapTuple		indexTuple;
+	Form_pg_index	indexForm;
+	
+	rel = heap_open(relOid, AccessExclusiveLock);
+
+	indexOid = get_relname_relid(indexName, rel->rd_rel->relnamespace);
+	
+	if (!OidIsValid(indexOid))
+		elog(ERROR, "ALTER TABLE: cannot find index \"%s\" for table \"%s\"",
+				indexName, NameStr(rel->rd_rel->relname));
+
+	indexTuple = SearchSysCache(INDEXRELID,
+								ObjectIdGetDatum(indexOid),
+								0, 0, 0);
+
+	if (!HeapTupleIsValid(indexTuple))
+		elog(ERROR, "Cache lookup failed for index %u",
+				indexOid);
+	indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
+
+	/*
+	 * If this is the same index the relation was previously
+	 * clustered on, no need to do anything.
+	 */
+	if (indexForm->indisclustered)
+	{
+		elog(NOTICE, "ALTER TABLE: table \"%s\" is already being clustered on index \"%s\"",
+				NameStr(rel->rd_rel->relname), indexName);
+		heap_close(rel, AccessExclusiveLock);
+		return;
+	}
+
+	pg_index = heap_openr(IndexRelationName, RowExclusiveLock);
+	
+	/*
+	 * Now check each index in the relation and set the bit where needed.
+	 */
+	foreach (index, RelationGetIndexList(rel))
+	{
+		HeapTuple       idxtuple;
+		Form_pg_index   idxForm;
+		
+		indexOid = lfirsto(index);
+		idxtuple = SearchSysCacheCopy(INDEXRELID,
+		  							  ObjectIdGetDatum(indexOid),
+									  0, 0, 0);
+		if (!HeapTupleIsValid(idxtuple))
+			elog(ERROR, "Cache lookup failed for index %u", indexOid);
+		idxForm = (Form_pg_index) GETSTRUCT(idxtuple);
+		/*
+		 * Unset the bit if set.  We know it's wrong because we checked
+		 * this earlier.
+		 */
+		if (idxForm->indisclustered)
+		{
+			idxForm->indisclustered = false;
+			simple_heap_update(pg_index, &idxtuple->t_self, idxtuple);
+			CatalogUpdateIndexes(pg_index, idxtuple);
+		}
+		else if (idxForm->indexrelid == indexForm->indexrelid)
+		{
+			idxForm->indisclustered = true;
+			simple_heap_update(pg_index, &idxtuple->t_self, idxtuple);
+			CatalogUpdateIndexes(pg_index, idxtuple);
+		}
+		heap_freetuple(idxtuple);
+	}
+	ReleaseSysCache(indexTuple);
+	heap_close(rel, AccessExclusiveLock);
+	heap_close(pg_index, RowExclusiveLock);
+}
+
 /*
  * ALTER TABLE CREATE TOAST TABLE
  */

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.407 2003/03/20 07:02:08 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.408 2003/03/20 18:52:47 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -1217,6 +1217,15 @@ AlterTableStmt:
 					n->name = $6;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> CLUSTER ON <indexname> */
+			| ALTER TABLE qualified_name CLUSTER ON name
+				{
+					AlterTableStmt *n = makeNode(AlterTableStmt);
+					n->subtype = 'L';
+					n->relation = $3;
+					n->name = $6;
+					$$ = (Node *)n;
+				}
 		;
 
 alter_column_default:

src/backend/tcop/utility.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.196 2003/03/20 07:02:11 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/utility.c,v 1.197 2003/03/20 18:52:48 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -609,6 +609,9 @@ ProcessUtility(Node *parsetree,
 						AlterTableOwner(relid,
 										get_usesysid(stmt->name));
 						break;
+					case 'L':	/* CLUSTER ON */
+						AlterTableClusterOn(relid, stmt->name);
+						break;
 					case 'o': /* ADD OIDS */
 						AlterTableAlterOids(relid,
 						 interpretInhOption(stmt->relation->inhOpt),

src/include/commands/tablecmds.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: tablecmds.h,v 1.11 2003/02/13 05:20:03 momjian Exp $
+ * $Id: tablecmds.h,v 1.12 2003/03/20 18:52:48 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,6 +43,8 @@ extern void AlterTableDropConstraint(Oid myrelid, bool recurse,
 						 const char *constrName,
 						 DropBehavior behavior);
 
+extern void AlterTableClusterOn(Oid relOid, const char *indexName);
+
 extern void AlterTableCreateToastTable(Oid relOid, bool silent);
 
 extern void AlterTableOwner(Oid relationOid, int32 newOwnerSysId);

src/include/nodes/parsenodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parsenodes.h,v 1.234 2003/03/20 07:02:11 momjian Exp $
+ * $Id: parsenodes.h,v 1.235 2003/03/20 18:52:48 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -704,6 +704,7 @@ typedef struct AlterTableStmt
 								 *	X = drop constraint
 								 *	E = create toast table
 								 *	U = change owner
+								 *	L = CLUSTER ON
 								 *  o = DROP OIDS
 								 *------------
 								 */

src/test/regress/expected/cluster.out

@@ -285,6 +285,18 @@ WHERE pg_class.oid=indexrelid
  clstr_tst_c
 (1 row)
 
+-- Try changing indisclustered
+ALTER TABLE clstr_tst CLUSTER ON clstr_tst_b_c;
+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    
+---------------
+ clstr_tst_b_c
+(1 row)
+
 -- 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

@@ -87,6 +87,14 @@ WHERE pg_class.oid=indexrelid
 	AND pg_class_2.relname = 'clstr_tst'
 	AND indisclustered;
 
+-- Try changing indisclustered
+ALTER TABLE clstr_tst CLUSTER ON clstr_tst_b_c;
+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);