bk commit into 5.0 tree (gkodinov:1.2227) BUG#21174

[kgeorge]

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ChangeSet@stripped, 2006-08-14 18:19:29+03:00, gkodinov@stripped +3 -0
  Bug #21174: Index degrades sort performance and 
               optimizer does not honor IGNORE INDEX
   - Allow an index to be used for sorting the table 
     instead of filesort only if it is not disabled by
     IGNORE INDEX.

  mysql-test/r/group_by.result@stripped, 2006-08-14 18:19:22+03:00, gkodinov@stripped +9 -0
    Bug #21174: Index degrades sort performance and 
                 optimizer does not honor IGNORE INDEX
     - test case

  mysql-test/t/group_by.test@stripped, 2006-08-14 18:19:23+03:00, gkodinov@stripped +12 -0
    Bug #21174: Index degrades sort performance and 
                 optimizer does not honor IGNORE INDEX
     - test case

  sql/sql_select.cc@stripped, 2006-08-14 18:19:24+03:00, gkodinov@stripped +2 -0
    Bug #21174: Index degrades sort performance and 
                 optimizer does not honor IGNORE INDEX
     - Allow an index to be used for sorting the table 
       instead of filesort only if it is not disabled by
       IGNORE INDEX.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	gkodinov
# Host:	macbook.gmz
# Root:	/Users/kgeorge/mysql/work/B21174-5.0-opt

--- 1.442/sql/sql_select.cc	2006-08-14 18:19:45 +03:00
+++ 1.443/sql/sql_select.cc	2006-08-14 18:19:45 +03:00
@@ -11498,6 +11498,8 @@ test_if_skip_sort_order(JOIN_TAB *tab,OR
     We must not try to use disabled keys.
   */
   usable_keys= table->s->keys_in_use;
+  /* we must not consider keys that are disabled by IGNORE INDEX */
+  usable_keys.intersect(table->keys_in_use_for_query);
 
   for (ORDER *tmp_order=order; tmp_order ; tmp_order=tmp_order->next)
   {

--- 1.69/mysql-test/r/group_by.result	2006-08-14 18:19:46 +03:00
+++ 1.70/mysql-test/r/group_by.result	2006-08-14 18:19:46 +03:00
@@ -821,3 +821,12 @@ a	b	real_b
 68	France	France
 DROP VIEW v1;
 DROP TABLE t1,t2;
+CREATE TABLE t1 (a INT, b INT, KEY(a));
+INSERT INTO t1 VALUES (1, 1), (2, 2), (3,3), (4,4);
+EXPLAIN SELECT a, SUM(b) FROM t1 GROUP BY a LIMIT 2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	a	5	NULL	4	
+EXPLAIN SELECT a, SUM(b) FROM t1 IGNORE INDEX (a) GROUP BY a LIMIT 2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	4	Using temporary; Using filesort
+DROP TABLE t1;

--- 1.57/mysql-test/t/group_by.test	2006-08-14 18:19:46 +03:00
+++ 1.58/mysql-test/t/group_by.test	2006-08-14 18:19:46 +03:00
@@ -655,3 +655,15 @@ where t2.b=v1.a GROUP BY t2.b;
 
 DROP VIEW v1;
 DROP TABLE t1,t2;
+
+#
+# Bug #21174: Index degrades sort performance and 
+#             optimizer does not honor IGNORE INDEX
+#
+CREATE TABLE t1 (a INT, b INT, KEY(a));
+INSERT INTO t1 VALUES (1, 1), (2, 2), (3,3), (4,4);
+
+EXPLAIN SELECT a, SUM(b) FROM t1 GROUP BY a LIMIT 2; 
+EXPLAIN SELECT a, SUM(b) FROM t1 IGNORE INDEX (a) GROUP BY a LIMIT 2;
+
+DROP TABLE t1;