Marginal hack to use a specialized hash function for dynahash hashtables

whose keys are OIDs.  The only one that looks particularly performance
critical is the relcache hashtable, but as long as we've got the function
we may as well use it wherever it's applicable.

4 files changed, 21 insertions, 8 deletions

diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index ab773de9c80..7c24e648af7 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.220 2005/04/14 20:03:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.221 2005/04/14 20:32:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1032,7 +1032,7 @@ LookupOpclassInfo(Oid operatorClassOid,
 		MemSet(&ctl, 0, sizeof(ctl));
 		ctl.keysize = sizeof(Oid);
 		ctl.entrysize = sizeof(OpClassCacheEnt);
-		ctl.hash = tag_hash;
+		ctl.hash = oid_hash;
 		OpClassCache = hash_create("Operator class cache", 64,
 								   &ctl, HASH_ELEM | HASH_FUNCTION);
 	}
@@ -2151,7 +2151,7 @@ RelationCacheInitialize(void)
 	MemSet(&ctl, 0, sizeof(ctl));
 	ctl.keysize = sizeof(Oid);
 	ctl.entrysize = sizeof(RelIdCacheEnt);
-	ctl.hash = tag_hash;
+	ctl.hash = oid_hash;
 	RelationIdCache = hash_create("Relcache by OID", INITRELCACHESIZE,
 								  &ctl, HASH_ELEM | HASH_FUNCTION);
 
diff --git a/src/backend/utils/cache/typcache.c b/src/backend/utils/cache/typcache.c
index 01990db8ad9..a46267643b5 100644
--- a/src/backend/utils/cache/typcache.c
+++ b/src/backend/utils/cache/typcache.c
@@ -36,7 +36,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/typcache.c,v 1.12 2005/04/14 20:03:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/typcache.c,v 1.13 2005/04/14 20:32:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -123,7 +123,7 @@ lookup_type_cache(Oid type_id, int flags)
 		MemSet(&ctl, 0, sizeof(ctl));
 		ctl.keysize = sizeof(Oid);
 		ctl.entrysize = sizeof(TypeCacheEntry);
-		ctl.hash = tag_hash;
+		ctl.hash = oid_hash;
 		TypeCacheHash = hash_create("Type information cache", 64,
 									&ctl, HASH_ELEM | HASH_FUNCTION);
 	}
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 0e9716de013..181da00fd7e 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/fmgr/fmgr.c,v 1.93 2005/03/31 22:46:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/fmgr/fmgr.c,v 1.94 2005/04/14 20:32:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -509,7 +509,7 @@ record_C_func(HeapTuple procedureTuple,
 		MemSet(&hash_ctl, 0, sizeof(hash_ctl));
 		hash_ctl.keysize = sizeof(Oid);
 		hash_ctl.entrysize = sizeof(CFuncHashTabEntry);
-		hash_ctl.hash = tag_hash;
+		hash_ctl.hash = oid_hash;
 		CFuncHash = hash_create("CFuncHash",
 								100,
 								&hash_ctl,
diff --git a/src/backend/utils/hash/hashfn.c b/src/backend/utils/hash/hashfn.c
index c27417d7d3b..24255f31e6e 100644
--- a/src/backend/utils/hash/hashfn.c
+++ b/src/backend/utils/hash/hashfn.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/hash/hashfn.c,v 1.22 2004/12/31 22:01:37 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/hash/hashfn.c,v 1.23 2005/04/14 20:32:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -40,3 +40,16 @@ tag_hash(const void *key, Size keysize)
 	return DatumGetUInt32(hash_any((const unsigned char *) key,
 								   (int) keysize));
 }
+
+/*
+ * oid_hash: hash function for keys that are OIDs
+ *
+ * (tag_hash works for this case too, but is slower)
+ */
+uint32
+oid_hash(const void *key, Size keysize)
+{
+	Assert(keysize == sizeof(Oid));
+	/* We don't actually bother to do anything to the OID value ... */
+	return (uint32) *((const Oid *) key);
+}