Revert patch, doesn't do what it should:

* %Disallow changing default expression of a SERIAL column

Dhanaraj M

doc/TODO

@@ -208,7 +208,11 @@ Data Types
   The positive modulus result returned by NUMERICs might be considered
   inaccurate, in one sense.
 
-* -Disallow changing DEFAULT expression of a SERIAL column
+* %Disallow changing DEFAULT expression of a SERIAL column?
+
+  This should be done only if the existing SERIAL problems cannot be
+  fixed.
+
 * %Disallow ALTER SEQUENCE changes for SERIAL sequences because pg_dump
   does not dump the changes
 * Fix data types where equality comparison isn't intuitive, e.g. box

doc/src/FAQ/TODO.html

@@ -190,7 +190,10 @@ first.
   inaccurate, in one sense.
 </p>
 <ul>
-  <li>-<em>Disallow changing DEFAULT expression of a SERIAL column</em>
+  <li>%Disallow changing DEFAULT expression of a SERIAL column?
+<p>  This should be done only if the existing SERIAL problems cannot be
+  fixed.
+</p>
   </li><li>%Disallow ALTER SEQUENCE changes for SERIAL sequences because pg_dump
   does not dump the changes
   </li><li>Fix data types where equality comparison isn't intuitive, e.g. box

src/backend/catalog/dependency.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/dependency.c,v 1.55 2006/06/27 03:21:54 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/dependency.c,v 1.56 2006/06/27 18:35:05 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1927,89 +1927,3 @@ getRelationDescription(StringInfo buffer, Oid relid)
 
 	ReleaseSysCache(relTup);
 }
-
-/* Recursively travel and search for the default sequence. Finally detach it */
-
-void performSequenceDefaultDeletion(const ObjectAddress *object,
-					DropBehavior behavior, int deleteFlag)
-{        
-        
-        ScanKeyData key[3];
-        int                     nkeys;
-        SysScanDesc scan;
-        HeapTuple       tup;
-        ObjectAddress otherObject;            
-	  Relation	depRel;
-	
-	  depRel = heap_open(DependRelationId, RowExclusiveLock);
-
-        ScanKeyInit(&key[0],
-                                Anum_pg_depend_classid,
-                                BTEqualStrategyNumber, F_OIDEQ,
-                                ObjectIdGetDatum(object->classId));
-        ScanKeyInit(&key[1],
-                                Anum_pg_depend_objid,
-                                BTEqualStrategyNumber, F_OIDEQ,
-                                ObjectIdGetDatum(object->objectId));
-        if (object->objectSubId != 0)
-        {
-               ScanKeyInit(&key[2],
-                                        Anum_pg_depend_objsubid,
-                                        BTEqualStrategyNumber, F_INT4EQ,
-                                        Int32GetDatum(object->objectSubId));
-                nkeys = 3;
-        }
-        else
-                nkeys = 2;
-
-        scan = systable_beginscan(depRel, DependDependerIndexId, true,
-                                                          SnapshotNow, nkeys, key);
-
-        while (HeapTupleIsValid(tup = systable_getnext(scan)))
-        {
-		
-                Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(tup);
-
-                otherObject.classId = foundDep->refclassid;
-                otherObject.objectId = foundDep->refobjid;
-                otherObject.objectSubId = foundDep->refobjsubid;
-
-		  /* Detach the default sequence from the relation */
-		  if(deleteFlag == 1)	
-		  {	
-                	simple_heap_delete(depRel, &tup->t_self);	
-			break;
-		  }
-
-                switch (foundDep->deptype)
-                {
-                        case DEPENDENCY_NORMAL:                        
-			{
-
-				if(getObjectClass(&otherObject) == OCLASS_CLASS)
-				{
-					/* Dont allow to change the default sequence */
-					if(deleteFlag == 2)	
-					{ 
-						systable_endscan(scan);
-				                heap_close(depRel, RowExclusiveLock);
-                                        	elog(ERROR, "%s is a SERIAL sequence. Can't alter the relation", getObjectDescription(&otherObject));
-	                                        return;
-					}
-					else /* Detach the default sequence from the relation */
-					{
-						performSequenceDefaultDeletion(&otherObject, behavior, 1);
-						systable_endscan(scan);
-						heap_close(depRel, RowExclusiveLock);
-        	                                return;					
-					}
-				}
-			}
-                		
-        	}
-	}
-
-        systable_endscan(scan);
-	heap_close(depRel, RowExclusiveLock);  	
-
-}

src/backend/catalog/heap.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.300 2006/06/27 03:21:54 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.301 2006/06/27 18:35:05 momjian Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -2133,50 +2133,3 @@ heap_truncate_find_FKs(List *relationIds)
 
 	return result;
 }
-
-
-/* Detach the default sequence and the relation */
-
-void 
-RemoveSequenceDefault(Oid relid, AttrNumber attnum,
-				  DropBehavior behavior, bool flag)
-{
-	Relation	attrdef_rel;
-	ScanKeyData scankeys[2];
-	SysScanDesc scan;
-	HeapTuple	tuple;
-
-	attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);
-
-	ScanKeyInit(&scankeys[0],
-				Anum_pg_attrdef_adrelid,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(relid));
-	ScanKeyInit(&scankeys[1],
-				Anum_pg_attrdef_adnum,
-				BTEqualStrategyNumber, F_INT2EQ,
-				Int16GetDatum(attnum));
-
-	scan = systable_beginscan(attrdef_rel, AttrDefaultIndexId, true,
-							  SnapshotNow, 2, scankeys);
-
-	/* There should be at most one matching tuple, but we loop anyway */
-	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
-	{
-		ObjectAddress object;
-
-		object.classId = AttrDefaultRelationId;
-		object.objectId = HeapTupleGetOid(tuple);
-		object.objectSubId = 0;
-
-		if(flag == true) /* Detach the sequence */
-  			performSequenceDefaultDeletion(&object, behavior, 0);
-		else	/* Don't allow to change the default sequence */
-			performSequenceDefaultDeletion(&object, behavior, 2);
-
-	}
-
-	systable_endscan(scan);
-	heap_close(attrdef_rel, RowExclusiveLock);
-
-}

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.187 2006/06/27 03:43:19 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.188 2006/06/27 18:35:05 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3404,11 +3404,6 @@ ATExecColumnDefault(Relation rel, const char *colName,
 	 * safety, but at present we do not expect anything to depend on the
 	 * default.
 	 */
-	if (newDefault)
-		RemoveSequenceDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false);
-	else 
-		RemoveSequenceDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, true);		
-
 	RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false);
 
 	if (newDefault)

src/include/catalog/dependency.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/dependency.h,v 1.24 2006/06/27 03:21:55 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/dependency.h,v 1.25 2006/06/27 18:35:05 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -207,7 +207,4 @@ extern void shdepDropOwned(List *relids, DropBehavior behavior);
 
 extern void shdepReassignOwned(List *relids, Oid newrole);
 
-extern void performSequenceDefaultDeletion(const ObjectAddress *object,
-					DropBehavior behavior, int deleteFlag);
-
 #endif   /* DEPENDENCY_H */

src/include/catalog/heap.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/heap.h,v 1.81 2006/06/27 03:21:55 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/heap.h,v 1.82 2006/06/27 18:35:05 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -97,7 +97,4 @@ extern void CheckAttributeNamesTypes(TupleDesc tupdesc, char relkind);
 
 extern void CheckAttributeType(const char *attname, Oid atttypid);
 
-extern void RemoveSequenceDefault(Oid relid, AttrNumber attnum,
-				  DropBehavior behavior, bool flag);
-
 #endif   /* HEAP_H */