Update of /cvsroot/monetdb/pathfinder/compiler/algebra/opt
In directory 23jxhf1.ch3.sourceforge.com:/tmp/cvs-serv24475/algebra/opt
Modified Files:
opt_thetajoin.c
Log Message:
-- Enable rowrank-thetajoin rewrite for a special case
(where the thetajoin behaves like a cross product).
U opt_thetajoin.c
Index: opt_thetajoin.c
===================================================================
RCS file: /cvsroot/monetdb/pathfinder/compiler/algebra/opt/opt_thetajoin.c,v
retrieving revision 1.44
retrieving revision 1.45
diff -u -d -r1.44 -r1.45
--- opt_thetajoin.c 12 Jun 2009 13:06:12 -0000 1.44
+++ opt_thetajoin.c 16 Jun 2009 14:01:25 -0000 1.45
@@ -1265,14 +1265,28 @@
break;
case la_rowrank:
- /* the following rewrite is incorrect as the thetajoin arguments
- filter out some rows from the cross product -- Not every
- iteration has the same number of rows anymore and thus row-
- ranking needs to take the result of the thetajoin into account.
*/
- break;
-#if 0
+ if (is_tj (L(p))) {
+ /******************** thetajoin check ************************/
+
+ unsigned int count = 0;
+ PFarray_t *pred = p->sem.thetajoin_opt.pred;
+
+ /* The following rewrite is incorrect if we have a real
+ thetajoin as the thetajoin arguments filter out some
+ rows from the cross product -- Not every group exists
+ anymore and thus row-ranking needs to take the result
+ of the thetajoin into account. */
+
+ /* Check if we have a cross product without selection. */
+ for (i = 0; i < PFarray_last (pred); i++)
+ if (PERS_AT(pred, i)) count++;
+ /* skip rewrite (see explanation above) */
+ if (count) break;
+
+ /******************** thetajoin check ************************/
+ }
/* fall through */
-#endif
+
case la_rank:
/* An expression that does not contain any sorting column
required by the rank operator is independent of the rank.
------------------------------------------------------------------------------
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