ALTER TABLE rewrite. New cool stuff:

* ALTER ... ADD COLUMN with defaults and NOT NULL constraints works per SQL
spec.  A default is implemented by rewriting the table with the new value
stored in each row.

* ALTER COLUMN TYPE.  You can change a column's datatype to anything you
want, so long as you can specify how to convert the old value.  Rewrites
the table.  (Possible future improvement: optimize no-op conversions such
as varchar(N) to varchar(N+1).)

* Multiple ALTER actions in a single ALTER TABLE command.  You can perform
any number of column additions, type changes, and constraint additions with
only one pass over the table contents.

Basic documentation provided in ALTER TABLE ref page, but some more docs
work is needed.

Original patch from Rod Taylor, additional work from Tom Lane.

1 files changed, 45 insertions, 36 deletions

diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index a10bbbd746c..b4bf08006eb 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.120 2004/03/23 19:35:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.121 2004/05/05 04:48:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -64,11 +64,7 @@ typedef struct
 
 
 static void cluster_rel(RelToCluster *rv, bool recheck);
-static Oid	make_new_heap(Oid OIDOldHeap, const char *NewName);
 static void copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex);
-static List *get_indexattr_list(Relation OldHeap, Oid OldIndex);
-static void rebuild_indexes(Oid OIDOldHeap, List *indexes);
-static void swap_relfilenodes(Oid r1, Oid r2);
 static List *get_tables_to_cluster(MemoryContext cluster_context);
 
 
@@ -479,7 +475,7 @@ rebuild_relation(Relation OldHeap, Oid indexOid)
 /*
  * Create the new table that we will fill with correctly-ordered data.
  */
-static Oid
+Oid
 make_new_heap(Oid OIDOldHeap, const char *NewName)
 {
 	TupleDesc	OldHeapDesc,
@@ -578,7 +574,7 @@ 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.
  */
-static List *
+List *
 get_indexattr_list(Relation OldHeap, Oid OldIndex)
 {
 	List	   *indexes = NIL;
@@ -621,7 +617,7 @@ 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).
  */
-static void
+void
 rebuild_indexes(Oid OIDOldHeap, List *indexes)
 {
 	List	   *elem;
@@ -646,10 +642,15 @@ rebuild_indexes(Oid OIDOldHeap, List *indexes)
 		 * matter: after the filenode swap the index will keep the
 		 * constraint status of the old index.
 		 */
-		newIndexOID = index_create(OIDOldHeap, newIndexName,
-								attrs->indexInfo, attrs->accessMethodOID,
-								   attrs->classOID, false,
-								   false, allowSystemTableMods);
+		newIndexOID = index_create(OIDOldHeap,
+								   newIndexName,
+								   attrs->indexInfo,
+								   attrs->accessMethodOID,
+								   attrs->classOID,
+								   false,
+								   false,
+								   allowSystemTableMods,
+								   false);
 		CommandCounterIncrement();
 
 		/* Swap the filenodes. */
@@ -698,7 +699,7 @@ rebuild_indexes(Oid OIDOldHeap, List *indexes)
  * Also swap any TOAST links, so that the toast data moves along with
  * the main-table data.
  */
-static void
+void
 swap_relfilenodes(Oid r1, Oid r2)
 {
 	Relation	relRelation,
@@ -789,9 +790,9 @@ swap_relfilenodes(Oid r1, Oid r2)
 	 * their new owning relations.	Otherwise the wrong one will get
 	 * dropped ...
 	 *
-	 * NOTE: for now, we can assume the new table will have a TOAST table if
-	 * and only if the old one does.  This logic might need work if we get
-	 * smarter about dropped columns.
+	 * NOTE: it is possible that only one table has a toast table; this
+	 * can happen in CLUSTER if there were dropped columns in the old table,
+	 * and in ALTER TABLE when adding or changing type of columns.
 	 *
 	 * NOTE: at present, a TOAST table's only dependency is the one on its
 	 * owning table.  If more are ever created, we'd need to use something
@@ -804,35 +805,43 @@ swap_relfilenodes(Oid r1, Oid r2)
 					toastobject;
 		long		count;
 
-		if (!(relform1->reltoastrelid && relform2->reltoastrelid))
-			elog(ERROR, "expected both swapped tables to have TOAST tables");
-
 		/* Delete old dependencies */
-		count = deleteDependencyRecordsFor(RelOid_pg_class,
-										   relform1->reltoastrelid);
-		if (count != 1)
-			elog(ERROR, "expected one dependency record for TOAST table, found %ld",
-				 count);
-		count = deleteDependencyRecordsFor(RelOid_pg_class,
-										   relform2->reltoastrelid);
-		if (count != 1)
-			elog(ERROR, "expected one dependency record for TOAST table, found %ld",
-				 count);
+		if (relform1->reltoastrelid)
+		{
+			count = deleteDependencyRecordsFor(RelOid_pg_class,
+											   relform1->reltoastrelid);
+			if (count != 1)
+				elog(ERROR, "expected one dependency record for TOAST table, found %ld",
+					 count);
+		}
+		if (relform2->reltoastrelid)
+		{
+			count = deleteDependencyRecordsFor(RelOid_pg_class,
+											   relform2->reltoastrelid);
+			if (count != 1)
+				elog(ERROR, "expected one dependency record for TOAST table, found %ld",
+					 count);
+		}
 
 		/* Register new dependencies */
 		baseobject.classId = RelOid_pg_class;
-		baseobject.objectId = r1;
 		baseobject.objectSubId = 0;
 		toastobject.classId = RelOid_pg_class;
-		toastobject.objectId = relform1->reltoastrelid;
 		toastobject.objectSubId = 0;
 
-		recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
-
-		baseobject.objectId = r2;
-		toastobject.objectId = relform2->reltoastrelid;
+		if (relform1->reltoastrelid)
+		{
+			baseobject.objectId = r1;
+			toastobject.objectId = relform1->reltoastrelid;
+			recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
+		}
 
-		recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
+		if (relform2->reltoastrelid)
+		{
+			baseobject.objectId = r2;
+			toastobject.objectId = relform2->reltoastrelid;
+			recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
+		}
 	}
 
 	/*