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

[kgeorge]

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ChangeSet@stripped, 2006-08-02 17:18:00+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/innodb_mysql.result@stripped, 2006-08-02 17:17:53+03:00, gkodinov@stripped +9
-0
    Bug #21174: Index degrades sort performance and 
                 optimizer does not honor IGNORE INDEX
     - test case.

  mysql-test/t/innodb_mysql.test@stripped, 2006-08-02 17:17:55+03:00, gkodinov@stripped +12
-0
    Bug #21174: Index degrades sort performance and 
                 optimizer does not honor IGNORE INDEX
     - test case. Note it must be over an InnoDB table as
       MyISAM tables don't support using only the index
       for scanning the table and not going to the row. i.e.
       keys_to_use_for_scanning() returns empty set for MyISAM.

  sql/sql_select.cc@stripped, 2006-08-02 17:17:55+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	2006-08-02 17:18:16 +03:00
+++ 1.443/sql/sql_select.cc	2006-08-02 17:18:16 +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)
   {

--- 1.6/mysql-test/r/innodb_mysql.result	2006-08-02 17:18:16 +03:00
+++ 1.7/mysql-test/r/innodb_mysql.result	2006-08-02 17:18:16 +03:00
@@ -297,3 +297,12 @@ explain select distinct f1, f2 from t1;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	range	NULL	PRIMARY	5	NULL	3	Using index for group-by; Using temporary
 drop table t1;
+CREATE TABLE t1 (a INT, b INT, KEY(a)) ENGINE = INNODB;
+INSERT INTO t1 VALUES (1, 1), (2, 2);
+EXPLAIN SELECT a, SUM(b) FROM t1 GROUP BY a ;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	index	NULL	a	5	NULL	2	
+EXPLAIN SELECT a, SUM(b) FROM t1 IGNORE INDEX (a) GROUP BY a;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	Using temporary; Using filesort
+DROP TABLE t1;

--- 1.6/mysql-test/t/innodb_mysql.test	2006-08-02 17:18:16 +03:00
+++ 1.7/mysql-test/t/innodb_mysql.test	2006-08-02 17:18:16 +03:00
@@ -255,3 +255,15 @@ explain select distinct f1 a, f1 b from 
 explain select distinct f1, f2 from t1;
 drop table t1;
 
+#
+# Bug #21174: Index degrades sort performance and 
+#             optimizer does not honor IGNORE INDEX
+#
+CREATE TABLE t1 (a INT, b INT, KEY(a)) ENGINE = INNODB;
+
+INSERT INTO t1 VALUES (1, 1), (2, 2);
+
+EXPLAIN SELECT a, SUM(b) FROM t1 GROUP BY a ; 
+EXPLAIN SELECT a, SUM(b) FROM t1 IGNORE INDEX (a) GROUP BY a;
+
+DROP TABLE t1;