Fix StoreCatalogInheritance1 to use 32bit inhseqno

alvherre · alvherre · commit 9a215fb4b5ec · 2018-01-19T10:15:08.000-03:00
For no apparent reason, this function was using a 16bit-wide inhseqno value, rather than the correct 32 bit width which is what is stored in the pg_inherits catalog. This becomes evident if you try to create a table with more than 65535 parents, because this error appears: ERROR: duplicate key value violates unique constraint «pg_inherits_relid_seqno_index» DETAIL: Key (inhrelid, inhseqno)=(329371, 0) already exists. Needless to say, having so many parents is an uncommon situations, which explains why this error has never been reported despite being having been introduced with the Postgres95 1.01 sources in commit d31084e: https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/commands/creatinh.c;hb=d31084e9d111#l349 Backpatch all the way back. David Rowley noticed this while reviewing a patch of mine. Discussion: https://postgr.es/m/CAKJS1f8Dn7swSEhOWwzZzssW7747YB=2Hi+T7uGud40dur69-g@mail.gmail.com
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
@@ -269,7 +269,7 @@ static void MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 static void MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel);
 static void StoreCatalogInheritance(Oid relationId, List *supers);
 static void StoreCatalogInheritance1(Oid relationId, Oid parentOid,
-						 int16 seqNumber, Relation inhRelation);
+						 int32 seqNumber, Relation inhRelation);
 static int	findAttrByName(const char *attributeName, List *schema);
 static void AlterIndexNamespaces(Relation classRel, Relation rel,
 				   Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved);
@@ -1900,7 +1900,7 @@ static void
 StoreCatalogInheritance(Oid relationId, List *supers)
 {
 	Relation	relation;
-	int16		seqNumber;
+	int32		seqNumber;
 	ListCell   *entry;
 
 	/*
@@ -1940,7 +1940,7 @@ StoreCatalogInheritance(Oid relationId, List *supers)
  */
 static void
 StoreCatalogInheritance1(Oid relationId, Oid parentOid,
-						 int16 seqNumber, Relation inhRelation)
+						 int32 seqNumber, Relation inhRelation)
 {
 	TupleDesc	desc = RelationGetDescr(inhRelation);
 	Datum		values[Natts_pg_inherits];
@@ -1954,7 +1954,7 @@ StoreCatalogInheritance1(Oid relationId, Oid parentOid,
 	 */
 	values[Anum_pg_inherits_inhrelid - 1] = ObjectIdGetDatum(relationId);
 	values[Anum_pg_inherits_inhparent - 1] = ObjectIdGetDatum(parentOid);
-	values[Anum_pg_inherits_inhseqno - 1] = Int16GetDatum(seqNumber);
+	values[Anum_pg_inherits_inhseqno - 1] = Int32GetDatum(seqNumber);
 
 	memset(nulls, 0, sizeof(nulls));
 
