> For me, it's better to prevent that from happening. So, attempts to
> DROP NOT NULL on the child must be rejected. The attached patch does
> that.
I'm sorry. Accidentaly i "--color"-ed the patch format. Attached the
correct patch.
Best Regards,
Ali Akbar
diff --git a/src/backend/catalog/pg_inherits.c b/src/backend/catalog/pg_inherits.c
index 1bd8a58b7f..74903a8f24 100644
--- a/src/backend/catalog/pg_inherits.c
+++ b/src/backend/catalog/pg_inherits.c
@@ -242,6 +242,40 @@ find_all_inheritors(Oid parentrelId, LOCKMODE lockmode, List **numparents)
}
+/*
+ * get_superclasses -
+ * Returns a list of relation OIDs of direct parents
+ */
+List *
+get_superclasses(Oid relationId)
+{
+ List *list = NIL;
+ Relation catalog;
+ SysScanDesc scan;
+ ScanKeyData skey;
+ HeapTuple inheritsTuple;
+ Oid inhparent;
+
+ catalog = heap_open(InheritsRelationId, AccessShareLock);
+ ScanKeyInit(&skey, Anum_pg_inherits_inhrelid, BTEqualStrategyNumber,
+ F_OIDEQ, ObjectIdGetDatum(relationId));
+ scan = systable_beginscan(catalog, InheritsRelidSeqnoIndexId, true,
+ NULL, 1, &skey);
+
+ while ((inheritsTuple = systable_getnext(scan)) != NULL)
+ {
+ inhparent = ((Form_pg_inherits) GETSTRUCT(inheritsTuple))->inhparent;
+ list = lappend_oid(list, inhparent);
+ }
+
+ systable_endscan(scan);
+
+ heap_close(catalog, AccessShareLock);
+
+ return list;
+}
+
+
/*
* has_subclass - does this relation have any children?
*
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d979ce266d..c76fc3715d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -5683,6 +5683,8 @@ ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
Relation attr_rel;
List *indexoidlist;
ListCell *indexoidscan;
+ List *parentlist;
+ ListCell *parentscan;
ObjectAddress address;
/*
@@ -5773,6 +5775,24 @@ ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
heap_close(parent, AccessShareLock);
}
+ /* If rel has parents, shoudn't drop NOT NULL if parent has the same */
+ parentlist = get_superclasses(RelationGetRelid(rel));
+ foreach(parentscan, parentlist) {
+ Oid parentId = lfirst_oid(parentscan);
+ Relation parent = heap_open(parentId, AccessShareLock);
+ TupleDesc tupDesc = RelationGetDescr(parent);
+ AttrNumber parent_attnum;
+
+ parent_attnum = get_attnum(parentId, colName);
+ if (parent_attnum != InvalidAttrNumber &&
+ TupleDescAttr(tupDesc, parent_attnum - 1)->attnotnull)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+ errmsg("column \"%s\" is marked NOT NULL in parent table",
+ colName)));
+ heap_close(parent, AccessShareLock);
+ }
+
/*
* Okay, actually perform the catalog change ... if needed
*/
diff --git a/src/include/catalog/pg_inherits_fn.h b/src/include/catalog/pg_inherits_fn.h
index 7743388899..291861b846 100644
--- a/src/include/catalog/pg_inherits_fn.h
+++ b/src/include/catalog/pg_inherits_fn.h
@@ -20,6 +20,7 @@
extern List *find_inheritance_children(Oid parentrelId, LOCKMODE lockmode);
extern List *find_all_inheritors(Oid parentrelId, LOCKMODE lockmode,
List **parents);
+extern List *get_superclasses(Oid relationId);
extern bool has_subclass(Oid relationId);
extern bool has_superclass(Oid relationId);
extern bool typeInheritsFrom(Oid subclassTypeId, Oid superclassTypeId);
