diff options
Diffstat (limited to 'mysql-test/t/group_by.test')
| -rw-r--r-- | mysql-test/t/group_by.test | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/mysql-test/t/group_by.test b/mysql-test/t/group_by.test index 531cec6b730..18e244d8152 100644 --- a/mysql-test/t/group_by.test +++ b/mysql-test/t/group_by.test @@ -996,8 +996,33 @@ EXPLAIN SELECT a FROM t1 WHERE a < 2 ORDER BY a; EXPLAIN SELECT a FROM t1 WHERE a < 2 GROUP BY a; EXPLAIN SELECT a FROM t1 IGNORE INDEX (PRIMARY,i2); EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR JOIN (PRIMARY,i2); + +--echo # +--echo # For this explain, the query plan is weird: if we are using +--echo # the primary key for reasons other than doing grouping, can't +--echo # GROUP BY code take advantage of this? Well, currently it doesnt: EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR GROUP BY (PRIMARY,i2) GROUP BY a; +--echo # Here's a proof it is really doing sorting: +flush status; +--disable_result_log +SELECT a FROM t1 IGNORE INDEX FOR GROUP BY (PRIMARY,i2) GROUP BY a; +--enable_result_log +show status like 'Sort_%'; +--echo # Proof ends. +--echo # + +--echo # For this explain, the query plan is weird: if we are using +--echo # the primary key for reasons other than doing sorting, can't +--echo # ORDER BY code take advantage of this? Well, currently it doesnt: EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a; +--echo # Here's a proof it is really doing sorting: +flush status; +--disable_result_log +SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a; +--enable_result_log +show status like 'Sort_%'; +--echo # Proof ends. +--echo # SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a; EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY) IGNORE INDEX FOR GROUP BY (i2) GROUP BY a; |