Create the planner mechanism for optimizing simple MIN and MAX queries

[postgresql] / src / backend / utils / cache / lsyscache.c

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 3abbf65fa4833d6ef99ece190603088a49b4fac6..2c4d20576a5552da22c9e6912c261d646a711798 100644 (file)
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.122 2005/03/31 22:46:14 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/cache/lsyscache.c,v 1.123 2005/04/11 23:06:56 tgl Exp $
  *
  * NOTES
  *       Eventually, the index information should go through here, too.
@@ -53,6 +53,31 @@ op_in_opclass(Oid opno, Oid opclass)
                                                                0, 0);
 }
 
+/*
+ * get_op_opclass_strategy
+ *
+ *             Get the operator's strategy number within the specified opclass,
+ *             or 0 if it's not a member of the opclass.
+ */
+int
+get_op_opclass_strategy(Oid opno, Oid opclass)
+{
+       HeapTuple       tp;
+       Form_pg_amop amop_tup;
+       int                     result;
+
+       tp = SearchSysCache(AMOPOPID,
+                                               ObjectIdGetDatum(opno),
+                                               ObjectIdGetDatum(opclass),
+                                               0, 0);
+       if (!HeapTupleIsValid(tp))
+               return 0;
+       amop_tup = (Form_pg_amop) GETSTRUCT(tp);
+       result = amop_tup->amopstrategy;
+       ReleaseSysCache(tp);
+       return result;
+}
+
 /*
  * get_op_opclass_properties
  *