Make ALTER COLUMN TYPE preserve clustered status for indexes it doesn't

modify.  Also fix a passel of problems with ALTER TABLE CLUSTER ON:
failure to check that the index is safe to cluster on (or even belongs
to the indicated rel, or even exists), and failure to broadcast a relcache
flush event when changing an index's state.

src/backend/commands/cluster.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.121 2004/05/05 04:48:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.122 2004/05/06 16:10:57 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -31,6 +31,7 @@
 #include "miscadmin.h"
 #include "utils/acl.h"
 #include "utils/fmgroids.h"
+#include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/syscache.h"
 #include "utils/relcache.h"
@@ -48,7 +49,6 @@ typedef struct
 	IndexInfo  *indexInfo;
 	Oid			accessMethodOID;
 	Oid		   *classOID;
-	bool		isclustered;
 } IndexAttrs;
 
 /*
@@ -246,8 +246,7 @@ cluster(ClusterStmt *stmt)
 static void
 cluster_rel(RelToCluster *rvtc, bool recheck)
 {
-	Relation	OldHeap,
-				OldIndex;
+	Relation	OldHeap;
 
 	/* Check for user-requested abort. */
 	CHECK_FOR_INTERRUPTS();
@@ -300,18 +299,41 @@ cluster_rel(RelToCluster *rvtc, bool recheck)
 	/*
 	 * We grab exclusive access to the target rel and index for the
 	 * duration of the transaction.  (This is redundant for the single-
-	 * transaction case, since cluster() already did it.)
+	 * transaction case, since cluster() already did it.)  The index
+	 * lock is taken inside check_index_is_clusterable.
 	 */
 	OldHeap = heap_open(rvtc->tableOid, AccessExclusiveLock);
 
-	OldIndex = index_open(rvtc->indexOid);
+	/* Check index is valid to cluster on */
+	check_index_is_clusterable(OldHeap, rvtc->indexOid);
+
+	/* rebuild_relation does all the dirty work */
+	rebuild_relation(OldHeap, rvtc->indexOid);
+
+	/* NB: rebuild_relation does heap_close() on OldHeap */
+}
+
+/*
+ * Verify that the specified index is a legitimate index to cluster on
+ *
+ * Side effect: obtains exclusive lock on the index.  The caller should
+ * already have exclusive lock on the table, so the index lock is likely
+ * redundant, but it seems best to grab it anyway to ensure the index
+ * definition can't change under us.
+ */
+void
+check_index_is_clusterable(Relation OldHeap, Oid indexOid)
+{
+	Relation	OldIndex;
+
+	OldIndex = index_open(indexOid);
 	LockRelation(OldIndex, AccessExclusiveLock);
 
 	/*
 	 * Check that index is in fact an index on the given relation
 	 */
 	if (OldIndex->rd_index == NULL ||
-		OldIndex->rd_index->indrelid != rvtc->tableOid)
+		OldIndex->rd_index->indrelid != RelationGetRelid(OldHeap))
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("\"%s\" is not an index for table \"%s\"",
@@ -386,11 +408,6 @@ cluster_rel(RelToCluster *rvtc, bool recheck)
 
 	/* Drop relcache refcnt on OldIndex, but keep lock */
 	index_close(OldIndex);
-
-	/* rebuild_relation does all the dirty work */
-	rebuild_relation(OldHeap, rvtc->indexOid);
-
-	/* NB: rebuild_relation does heap_close() on OldHeap */
 }
 
 /*
@@ -410,13 +427,14 @@ void
 rebuild_relation(Relation OldHeap, Oid indexOid)
 {
 	Oid			tableOid = RelationGetRelid(OldHeap);
+	Oid			oldClusterIndex;
 	List	   *indexes;
 	Oid			OIDNewHeap;
 	char		NewHeapName[NAMEDATALEN];
 	ObjectAddress object;
 
 	/* Save the information about all indexes on the relation. */
-	indexes = get_indexattr_list(OldHeap, indexOid);
+	indexes = get_indexattr_list(OldHeap, &oldClusterIndex);
 
 	/* Close relcache entry, but keep lock until transaction commit */
 	heap_close(OldHeap, NoLock);
@@ -469,7 +487,8 @@ rebuild_relation(Relation OldHeap, Oid indexOid)
 	 * Recreate each index on the relation.  We do not need
 	 * CommandCounterIncrement() because rebuild_indexes does it.
 	 */
-	rebuild_indexes(tableOid, indexes);
+	rebuild_indexes(tableOid, indexes,
+					(OidIsValid(indexOid) ? indexOid : oldClusterIndex));
 }
 
 /*
@@ -572,14 +591,18 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex)
 
 /*
  * Get the necessary info about the indexes of the relation and
- * return a list of IndexAttrs structures.
+ * return a list of IndexAttrs structures.  Also, *OldClusterIndex
+ * is set to the OID of the existing clustered index, or InvalidOid
+ * if there is none.
  */
 List *
-get_indexattr_list(Relation OldHeap, Oid OldIndex)
+get_indexattr_list(Relation OldHeap, Oid *OldClusterIndex)
 {
 	List	   *indexes = NIL;
 	List	   *indlist;
 
+	*OldClusterIndex = InvalidOid;
+
 	/* Ask the relcache to produce a list of the indexes of the old rel */
 	foreach(indlist, RelationGetIndexList(OldHeap))
 	{
@@ -598,16 +621,12 @@ get_indexattr_list(Relation OldHeap, Oid OldIndex)
 			palloc(sizeof(Oid) * attrs->indexInfo->ii_NumIndexAttrs);
 		memcpy(attrs->classOID, oldIndex->rd_index->indclass,
 			   sizeof(Oid) * attrs->indexInfo->ii_NumIndexAttrs);
-		/* We adjust the isclustered attribute to correct new state */
-		attrs->isclustered = (indexOID == OldIndex);
+		if (oldIndex->rd_index->indisclustered)
+			*OldClusterIndex = indexOID;
 
 		index_close(oldIndex);
 
-		/*
-		 * Cons the gathered data into the list.  We do not care about
-		 * ordering, and this is more efficient than append.
-		 */
-		indexes = lcons(attrs, indexes);
+		indexes = lappend(indexes, attrs);
 	}
 
 	return indexes;
@@ -616,17 +635,22 @@ get_indexattr_list(Relation OldHeap, Oid OldIndex)
 /*
  * Create new indexes and swap the filenodes with old indexes.	Then drop
  * the new index (carrying the old index filenode along).
+ *
+ * OIDClusterIndex is the OID of the index to be marked as clustered, or
+ * InvalidOid if none should be marked clustered.
  */
 void
-rebuild_indexes(Oid OIDOldHeap, List *indexes)
+rebuild_indexes(Oid OIDOldHeap, List *indexes, Oid OIDClusterIndex)
 {
 	List	   *elem;
 
 	foreach(elem, indexes)
 	{
 		IndexAttrs *attrs = (IndexAttrs *) lfirst(elem);
+		Oid			oldIndexOID = attrs->indexOID;
 		Oid			newIndexOID;
 		char		newIndexName[NAMEDATALEN];
+		bool		isclustered;
 		ObjectAddress object;
 		Form_pg_index index;
 		HeapTuple	tuple;
@@ -634,7 +658,7 @@ rebuild_indexes(Oid OIDOldHeap, List *indexes)
 
 		/* Create the new index under a temporary name */
 		snprintf(newIndexName, sizeof(newIndexName),
-				 "pg_temp_%u", attrs->indexOID);
+				 "pg_temp_%u", oldIndexOID);
 
 		/*
 		 * The new index will have primary and constraint status set to
@@ -654,26 +678,30 @@ rebuild_indexes(Oid OIDOldHeap, List *indexes)
 		CommandCounterIncrement();
 
 		/* Swap the filenodes. */
-		swap_relfilenodes(attrs->indexOID, newIndexOID);
+		swap_relfilenodes(oldIndexOID, newIndexOID);
 
 		CommandCounterIncrement();
 
 		/*
 		 * Make sure that indisclustered is correct: it should be set only
-		 * for the index we just clustered on.
+		 * for the index specified by the caller.
 		 */
+		isclustered = (oldIndexOID == OIDClusterIndex);
+
 		pg_index = heap_openr(IndexRelationName, RowExclusiveLock);
 		tuple = SearchSysCacheCopy(INDEXRELID,
-								   ObjectIdGetDatum(attrs->indexOID),
+								   ObjectIdGetDatum(oldIndexOID),
 								   0, 0, 0);
 		if (!HeapTupleIsValid(tuple))
-			elog(ERROR, "cache lookup failed for index %u", attrs->indexOID);
+			elog(ERROR, "cache lookup failed for index %u", oldIndexOID);
 		index = (Form_pg_index) GETSTRUCT(tuple);
-		if (index->indisclustered != attrs->isclustered)
+		if (index->indisclustered != isclustered)
 		{
-			index->indisclustered = attrs->isclustered;
+			index->indisclustered = isclustered;
 			simple_heap_update(pg_index, &tuple->t_self, tuple);
 			CatalogUpdateIndexes(pg_index, tuple);
+			/* Ensure we see the update in the index's relcache entry */
+			CacheInvalidateRelcacheByRelid(oldIndexOID);
 		}
 		heap_freetuple(tuple);
 		heap_close(pg_index, RowExclusiveLock);

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.103 2004/05/05 04:48:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.104 2004/05/06 16:10:57 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2099,12 +2099,13 @@ ATRewriteTables(List **wqueue)
 			Oid			OIDNewHeap;
 			char		NewHeapName[NAMEDATALEN];
 			List	   *indexes;
+			Oid			oldClusterIndex;
 			Relation	OldHeap;
 			ObjectAddress	object;
 
 			/* Save the information about all indexes on the relation. */
 			OldHeap = heap_open(tab->relid, NoLock);
-			indexes = get_indexattr_list(OldHeap, InvalidOid);
+			indexes = get_indexattr_list(OldHeap, &oldClusterIndex);
 			heap_close(OldHeap, NoLock);
 
 			/*
@@ -2148,7 +2149,7 @@ ATRewriteTables(List **wqueue)
 			 * Rebuild each index on the relation.  We do not need
 			 * CommandCounterIncrement() because rebuild_indexes does it.
 			 */
-			rebuild_indexes(tab->relid, indexes);
+			rebuild_indexes(tab->relid, indexes, oldClusterIndex);
 		}
 		else
 		{
@@ -5004,6 +5005,9 @@ ATExecClusterOn(Relation rel, const char *indexName)
 				 errmsg("index \"%s\" for table \"%s\" does not exist",
 						indexName, RelationGetRelationName(rel))));
 
+	/* Check index is valid to cluster on */
+	check_index_is_clusterable(rel, indexOid);
+
 	indexTuple = SearchSysCache(INDEXRELID,
 								ObjectIdGetDatum(indexOid),
 								0, 0, 0);
@@ -5050,12 +5054,16 @@ ATExecClusterOn(Relation rel, const char *indexName)
 			idxForm->indisclustered = false;
 			simple_heap_update(pg_index, &idxtuple->t_self, idxtuple);
 			CatalogUpdateIndexes(pg_index, idxtuple);
+			/* Ensure we see the update in the index's relcache entry */
+			CacheInvalidateRelcacheByRelid(indexOid);
 		}
 		else if (idxForm->indexrelid == indexForm->indexrelid)
 		{
 			idxForm->indisclustered = true;
 			simple_heap_update(pg_index, &idxtuple->t_self, idxtuple);
 			CatalogUpdateIndexes(pg_index, idxtuple);
+			/* Ensure we see the update in the index's relcache entry */
+			CacheInvalidateRelcacheByRelid(indexOid);
 		}
 		heap_freetuple(idxtuple);
 	}

src/backend/utils/cache/inval.c

@@ -74,7 +74,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/inval.c,v 1.60 2004/02/10 01:55:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/inval.c,v 1.61 2004/05/06 16:10:57 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -88,6 +88,7 @@
 #include "utils/inval.h"
 #include "utils/memutils.h"
 #include "utils/relcache.h"
+#include "utils/syscache.h"
 
 
 /*
@@ -765,6 +766,26 @@ CacheInvalidateRelcacheByTuple(HeapTuple classTuple)
 	RegisterRelcacheInvalidation(databaseId, relationId, rnode);
 }
 
+/*
+ * CacheInvalidateRelcacheByRelid
+ *		As above, but relation is identified by passing its OID.
+ *		This is the least efficient of the three options; use one of
+ *		the above routines if you have a Relation or pg_class tuple.
+ */
+void
+CacheInvalidateRelcacheByRelid(Oid relid)
+{
+	HeapTuple	tup;
+
+	tup = SearchSysCache(RELOID,
+						 ObjectIdGetDatum(relid),
+						 0, 0, 0);
+	if (!HeapTupleIsValid(tup))
+		elog(ERROR, "cache lookup failed for relation %u", relid);
+	CacheInvalidateRelcacheByTuple(tup);
+	ReleaseSysCache(tup);
+}
+
 /*
  * CacheRegisterSyscacheCallback
  *		Register the specified function to be called for all future

src/include/commands/cluster.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/commands/cluster.h,v 1.21 2004/05/05 04:48:47 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/commands/cluster.h,v 1.22 2004/05/06 16:10:57 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -19,10 +19,12 @@
 
 extern void cluster(ClusterStmt *stmt);
 
+extern void check_index_is_clusterable(Relation OldHeap, Oid indexOid);
 extern void rebuild_relation(Relation OldHeap, Oid indexOid);
 extern Oid	make_new_heap(Oid OIDOldHeap, const char *NewName);
-extern List *get_indexattr_list(Relation OldHeap, Oid OldIndex);
-extern void rebuild_indexes(Oid OIDOldHeap, List *indexes);
+extern List *get_indexattr_list(Relation OldHeap, Oid *OldClusterIndex);
+extern void rebuild_indexes(Oid OIDOldHeap, List *indexes,
+							Oid OIDClusterIndex);
 extern void swap_relfilenodes(Oid r1, Oid r2);
 
 #endif   /* CLUSTER_H */

src/include/utils/inval.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/utils/inval.h,v 1.30 2004/02/10 01:55:26 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/inval.h,v 1.31 2004/05/06 16:10:57 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -32,6 +32,8 @@ extern void CacheInvalidateRelcache(Relation relation);
 
 extern void CacheInvalidateRelcacheByTuple(HeapTuple classTuple);
 
+extern void CacheInvalidateRelcacheByRelid(Oid relid);
+
 extern void CacheRegisterSyscacheCallback(int cacheid,
 							  CacheCallbackFunction func,
 							  Datum arg);