Simplify coding to detach constraints when detaching partition

The original coding was too baroque and led to an use-after-release
mistake, noticed by buildfarm member prion.

Discussion: https://postgr.es/m/21693.1548305934@sss.pgh.pa.us

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 738c1781078261dd568a4d2d4daa9d4433012257..887c19c3eff9c79916d579d3ce09454678cfc0ab 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -15106,24 +15106,14 @@ ATExecDetachPartition(Relation rel, RangeVar *name)
                idx = index_open(idxid, AccessExclusiveLock);
                IndexSetParentIndex(idx, InvalidOid);
                update_relispartition(classRel, idxid, false);
-               index_close(idx, NoLock);
-
-               /*
-                * Detach any constraints associated with the index too.  Only UNIQUE
-                * and PRIMARY KEY index constraints can be inherited, so no need
-                * to check for others.
-                */
-               if (!idx->rd_index->indisprimary && !idx->rd_index->indisunique)
-                       continue;
 
+               /* If there's a constraint associated with the index, detach it too */
                constrOid = get_relation_idx_constraint_oid(RelationGetRelid(partRel),
                                                                                                        idxid);
-               if (!OidIsValid(constrOid))
-                       elog(ERROR, "missing pg_constraint entry of index \"%s\" of partition \"%s\"",
-                                RelationGetRelationName(idx),
-                                RelationGetRelationName(partRel));
+               if (OidIsValid(constrOid))
+                       ConstraintSetParentConstraint(constrOid, InvalidOid);
 
-               ConstraintSetParentConstraint(constrOid, InvalidOid);
+               index_close(idx, NoLock);
        }
        table_close(classRel, RowExclusiveLock);