Add a hash function for "numeric". Mark the equality operator for

numerics as "oprcanhash", and make the corresponding system catalog
updates. As a result, hash indexes, hashed aggregation, and hash
joins can now be used with the numeric type. Bump the catversion.

The only tricky aspect to doing this is writing a correct hash
function: it's possible for two Numerics to be equal according to
their equality operator, but have different in-memory bit patterns.
To cope with this, the hash function doesn't consider the Numeric's
"scale" or "sign", and explictly skips any leading or trailing
zeros in the Numeric's digit buffer (the current implementation
should suppress any such zeros, but it seems unwise to rely upon
this). See discussion on pgsql-patches for more details.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/include/catalog/pg_opclass.h b/src/include/catalog/pg_opclass.h
index 2df9b8241a..28fed11301 100644
--- a/src/include/catalog/pg_opclass.h
+++ b/src/include/catalog/pg_opclass.h
@@ -28,7 +28,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_opclass.h,v 1.75 2007/04/02 03:49:40 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_opclass.h,v 1.76 2007/05/08 18:56:47 neilc Exp $
  *
  * NOTES
  *	  the genbki.sh script reads this file and generates .bki
@@ -129,6 +129,7 @@ DATA(insert (	405		macaddr_ops			PGNSP PGUID 1985  829 t 0 ));
 DATA(insert (	403		name_ops			PGNSP PGUID 1986   19 t 0 ));
 DATA(insert (	405		name_ops			PGNSP PGUID 1987   19 t 0 ));
 DATA(insert (	403		numeric_ops			PGNSP PGUID 1988 1700 t 0 ));
+DATA(insert (	405		numeric_ops			PGNSP PGUID 1998 1700 t 0 ));
 DATA(insert OID = 1981 ( 403	oid_ops		PGNSP PGUID 1989   26 t 0 ));
 #define OID_BTREE_OPS_OID 1981
 DATA(insert (	405		oid_ops				PGNSP PGUID 1990   26 t 0 ));