Bug #22781: SQL_BIG_RESULT fails to influence sort plan

 Currently SQL_BIG_RESULT is checked only at compile time.
 However, additional optimizations may take place after
 this check that change the sort method from 'filesort'
 to sorting via index. As a result the actual plan
 executed is not the one specified by the SQL_BIG_RESULT
 hint. Similarly, there is no such test when executing
 EXPLAIN, resulting in incorrect output.
 The patch corrects the problem by testing for
 SQL_BIG_RESULT both during the explain and execution
 phases.


mysql-test/r/bdb.result:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - updated sql_big_result testcase
mysql-test/r/group_by.result:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - test case with MyISAM
mysql-test/r/innodb.result:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - updated sql_big_result testcase
mysql-test/r/innodb_mysql.result:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - test case with InnoDB
mysql-test/r/myisam.result:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - updated sql_big_result testcase
mysql-test/t/group_by.test:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - test case with MyISAM
mysql-test/t/innodb_mysql.test:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - test case with InnoDB
sql/sql_select.cc:
  Bug #22781: SQL_BIG_RESULT fails to influence sort plan
   - When SQL_BIG_RESULT is specified, disable the optimization performed
  at execution/explain time that decides to use an index instead
  of filesort.

1 files changed, 22 insertions, 0 deletions

diff --git a/mysql-test/t/group_by.test b/mysql-test/t/group_by.test
index ce1e4e59600..5d47f64f3d1 100644
--- a/mysql-test/t/group_by.test
+++ b/mysql-test/t/group_by.test
@@ -655,3 +655,25 @@ where t2.b=v1.a GROUP BY t2.b;
 
 DROP VIEW v1;
 DROP TABLE t1,t2;
+
+#
+# Bug#22781: SQL_BIG_RESULT fails to influence sort plan
+#
+CREATE TABLE t1 (a INT PRIMARY KEY, b INT, key (b));
+
+INSERT INTO t1 VALUES (1,      1);
+INSERT INTO t1 SELECT  a + 1 , MOD(a + 1 , 20) FROM t1;
+INSERT INTO t1 SELECT  a + 2 , MOD(a + 2 , 20) FROM t1;
+INSERT INTO t1 SELECT  a + 4 , MOD(a + 4 , 20) FROM t1;
+INSERT INTO t1 SELECT  a + 8 , MOD(a + 8 , 20) FROM t1;
+INSERT INTO t1 SELECT  a + 16, MOD(a + 16, 20) FROM t1;
+INSERT INTO t1 SELECT  a + 32, MOD(a + 32, 20) FROM t1;
+INSERT INTO t1 SELECT  a + 64, MOD(a + 64, 20) FROM t1;
+
+SELECT MIN(b), MAX(b) from t1;
+
+EXPLAIN SELECT b, sum(1) FROM t1 GROUP BY b;
+EXPLAIN SELECT SQL_BIG_RESULT b, sum(1) FROM t1 GROUP BY b;
+SELECT b, sum(1) FROM t1 GROUP BY b;
+SELECT SQL_BIG_RESULT b, sum(1) FROM t1 GROUP BY b;
+DROP TABLE t1;