From a635c08fa10fe545d723bcec6eb73bfdca07e2c0 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 30 Jan 2007 01:33:36 +0000
Subject: Add support for cross-type hashing in hash index searches and hash
 joins. Hashing for aggregation purposes still needs work, so it's not time to
 mark any cross-type operators as hashable for general use, but these cases
 work if the operators are so marked by hand in the system catalogs.

---
 src/backend/access/hash/hashutil.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

(limited to 'src/backend/access/hash/hashutil.c')

diff --git a/src/backend/access/hash/hashutil.c b/src/backend/access/hash/hashutil.c
index eadbe7aabe..afa7c09a53 100644
--- a/src/backend/access/hash/hashutil.c
+++ b/src/backend/access/hash/hashutil.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/hash/hashutil.c,v 1.50 2007/01/05 22:19:22 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/hash/hashutil.c,v 1.51 2007/01/30 01:33:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,6 +18,7 @@
 #include "access/hash.h"
 #include "access/reloptions.h"
 #include "executor/execdebug.h"
+#include "utils/lsyscache.h"
 
 
 /*
@@ -63,6 +64,9 @@ _hash_checkqual(IndexScanDesc scan, IndexTuple itup)
 
 /*
  * _hash_datum2hashkey -- given a Datum, call the index's hash procedure
+ *
+ * The Datum is assumed to be of the index's column type, so we can use the
+ * "primary" hash procedure that's tracked for us by the generic index code.
  */
 uint32
 _hash_datum2hashkey(Relation rel, Datum key)
@@ -75,6 +79,31 @@ _hash_datum2hashkey(Relation rel, Datum key)
 	return DatumGetUInt32(FunctionCall1(procinfo, key));
 }
 
+/*
+ * _hash_datum2hashkey_type -- given a Datum of a specified type,
+ *			hash it in a fashion compatible with this index
+ *
+ * This is much more expensive than _hash_datum2hashkey, so use it only in
+ * cross-type situations.
+ */
+uint32
+_hash_datum2hashkey_type(Relation rel, Datum key, Oid keytype)
+{
+	RegProcedure hash_proc;
+
+	/* XXX assumes index has only one attribute */
+	hash_proc = get_opfamily_proc(rel->rd_opfamily[0],
+								  keytype,
+								  keytype,
+								  HASHPROC);
+	if (!RegProcedureIsValid(hash_proc))
+		elog(ERROR, "missing support function %d(%u,%u) for index \"%s\"",
+			 HASHPROC, keytype, keytype,
+			 RelationGetRelationName(rel));
+
+	return DatumGetUInt32(OidFunctionCall1(hash_proc, key));
+}
+
 /*
  * _hash_hashkey2bucket -- determine which bucket the hashkey maps to.
  */
-- 
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