Change get_constraint_index() to use pg_constraint.conindid

It was still using a scan of pg_depend instead of using the conindid
column that has been added since.

Since it is now just a catalog lookup wrapper and not related to
pg_depend, move from pg_depend.c to lsyscache.c.

Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/flat/4688d55c-9a2e-9a5a-d166-5f24fe0bf8db%40enterprisedb.com

src/backend/catalog/pg_depend.c

@@ -968,75 +968,6 @@ getIdentitySequence(Oid relid, AttrNumber attnum, bool missing_ok)
 	return linitial_oid(seqlist);
 }
 
-/*
- * get_constraint_index
- *		Given the OID of a unique, primary-key, or exclusion constraint,
- *		return the OID of the underlying index.
- *
- * Return InvalidOid if the index couldn't be found; this suggests the
- * given OID is bogus, but we leave it to caller to decide what to do.
- */
-Oid
-get_constraint_index(Oid constraintId)
-{
-	Oid			indexId = InvalidOid;
-	Relation	depRel;
-	ScanKeyData key[3];
-	SysScanDesc scan;
-	HeapTuple	tup;
-
-	/* Search the dependency table for the dependent index */
-	depRel = table_open(DependRelationId, AccessShareLock);
-
-	ScanKeyInit(&key[0],
-				Anum_pg_depend_refclassid,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(ConstraintRelationId));
-	ScanKeyInit(&key[1],
-				Anum_pg_depend_refobjid,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(constraintId));
-	ScanKeyInit(&key[2],
-				Anum_pg_depend_refobjsubid,
-				BTEqualStrategyNumber, F_INT4EQ,
-				Int32GetDatum(0));
-
-	scan = systable_beginscan(depRel, DependReferenceIndexId, true,
-							  NULL, 3, key);
-
-	while (HeapTupleIsValid(tup = systable_getnext(scan)))
-	{
-		Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(tup);
-
-		/*
-		 * We assume any internal dependency of an index on the constraint
-		 * must be what we are looking for.
-		 */
-		if (deprec->classid == RelationRelationId &&
-			deprec->objsubid == 0 &&
-			deprec->deptype == DEPENDENCY_INTERNAL)
-		{
-			char		relkind = get_rel_relkind(deprec->objid);
-
-			/*
-			 * This is pure paranoia; there shouldn't be any other relkinds
-			 * dependent on a constraint.
-			 */
-			if (relkind != RELKIND_INDEX &&
-				relkind != RELKIND_PARTITIONED_INDEX)
-				continue;
-
-			indexId = deprec->objid;
-			break;
-		}
-	}
-
-	systable_endscan(scan);
-	table_close(depRel, AccessShareLock);
-
-	return indexId;
-}
-
 /*
  * get_index_constraint
  *		Given the OID of an index, return the OID of the owning unique,

src/backend/commands/tablecmds.c

@@ -26,7 +26,6 @@
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/catalog.h"
-#include "catalog/dependency.h"
 #include "catalog/heap.h"
 #include "catalog/index.h"
 #include "catalog/namespace.h"

src/backend/optimizer/util/plancat.c

@@ -26,7 +26,6 @@
 #include "access/transam.h"
 #include "access/xlog.h"
 #include "catalog/catalog.h"
-#include "catalog/dependency.h"
 #include "catalog/heap.h"
 #include "catalog/index.h"
 #include "catalog/pg_am.h"

src/backend/utils/adt/ruleutils.c

@@ -24,7 +24,6 @@
 #include "access/relation.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "catalog/dependency.h"
 #include "catalog/pg_aggregate.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_authid.h"
@@ -2140,7 +2139,7 @@ pg_get_constraintdef_worker(Oid constraintId, bool fullCommand,
 
 				appendStringInfoChar(&buf, ')');
 
-				indexId = get_constraint_index(constraintId);
+				indexId = conForm->conindid;
 
 				/* Build including column list (from pg_index.indkeys) */
 				indtup = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexId));

src/backend/utils/cache/lsyscache.c

@@ -1094,6 +1094,33 @@ get_constraint_name(Oid conoid)
 		return NULL;
 }
 
+/*
+ * get_constraint_index
+ *		Given the OID of a unique, primary-key, or exclusion constraint,
+ *		return the OID of the underlying index.
+ *
+ * Return InvalidOid if the index couldn't be found; this suggests the
+ * given OID is bogus, but we leave it to caller to decide what to do.
+ */
+Oid
+get_constraint_index(Oid conoid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(CONSTROID, ObjectIdGetDatum(conoid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_constraint contup = (Form_pg_constraint) GETSTRUCT(tp);
+		Oid			result;
+
+		result = contup->conindid;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return InvalidOid;
+}
+
 /*				---------- LANGUAGE CACHE ----------					 */
 
 char *

src/include/catalog/dependency.h

@@ -235,8 +235,6 @@ extern bool sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId)
 extern List *getOwnedSequences(Oid relid);
 extern Oid	getIdentitySequence(Oid relid, AttrNumber attnum, bool missing_ok);
 
-extern Oid	get_constraint_index(Oid constraintId);
-
 extern Oid	get_index_constraint(Oid indexId);
 
 extern List *get_index_ref_constraints(Oid indexId);

src/include/utils/lsyscache.h

@@ -96,6 +96,7 @@ extern Oid	get_cast_oid(Oid sourcetypeid, Oid targettypeid, bool missing_ok);
 extern char *get_collation_name(Oid colloid);
 extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
+extern Oid	get_constraint_index(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
 extern Oid	get_opclass_input_type(Oid opclass);