Fix StoreCatalogInheritance1 to use 32bit inhseqno

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 d31084e9d111:
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
index 5541fcbd54eefd135f310c1046be2408c65954de..fd457ab1b56f1d7e505a203431dc6fc4bf8d2329 100644 (file)
--- 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));