diff options
Diffstat (limited to 'mysql-test/r/group_by.result')
| -rw-r--r-- | mysql-test/r/group_by.result | 35 |
1 files changed, 33 insertions, 2 deletions
diff --git a/mysql-test/r/group_by.result b/mysql-test/r/group_by.result index 7f32643b727..f55489b7d93 100644 --- a/mysql-test/r/group_by.result +++ b/mysql-test/r/group_by.result @@ -1346,12 +1346,43 @@ id select_type table type possible_keys key key_len ref rows Extra EXPLAIN SELECT a FROM t1 IGNORE INDEX FOR JOIN (PRIMARY,i2); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 144 +# +# For this explain, the query plan is weird: if we are using +# the primary key for reasons other than doing grouping, can't +# 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; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 index NULL PRIMARY 4 NULL 144 Using index +1 SIMPLE t1 index NULL PRIMARY 4 NULL 144 Using index; Using filesort +# Here's a proof it is really doing sorting: +flush status; +SELECT a FROM t1 IGNORE INDEX FOR GROUP BY (PRIMARY,i2) GROUP BY a; +show status like 'Sort_%'; +Variable_name Value +Sort_merge_passes 0 +Sort_priority_queue_sorts 0 +Sort_range 0 +Sort_rows 144 +Sort_scan 1 +# Proof ends. +# +# For this explain, the query plan is weird: if we are using +# the primary key for reasons other than doing sorting, can't +# 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; id select_type table type possible_keys key key_len ref rows Extra -1 SIMPLE t1 index NULL PRIMARY 4 NULL 144 Using index +1 SIMPLE t1 index NULL PRIMARY 4 NULL 144 Using index; Using filesort +# Here's a proof it is really doing sorting: +flush status; +SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a; +show status like 'Sort_%'; +Variable_name Value +Sort_merge_passes 0 +Sort_priority_queue_sorts 0 +Sort_range 0 +Sort_rows 144 +Sort_scan 1 +# Proof ends. +# SELECT a FROM t1 IGNORE INDEX FOR ORDER BY (PRIMARY,i2) ORDER BY a; a 1 |