diff --git a/mysql-test/r/order_by.result b/mysql-test/r/order_by.result index 8d09686b7d3..a056e1244e6 100644 --- a/mysql-test/r/order_by.result +++ b/mysql-test/r/order_by.result @@ -926,3 +926,12 @@ NULL 2 3 DROP TABLE t1,t2,t3,t4; +CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a), UNIQUE KEY b (b)); +INSERT INTO t1 VALUES (1,1),(2,2); +CREATE TABLE t2 (a INT, b INT, KEY a (a,b)); +INSERT INTO t2 VALUES (1,1),(1,2),(2,1),(2,2); +EXPLAIN SELECT 1 FROM t1,t2 WHERE t1.b=2 AND t1.a=t2.a ORDER BY t2.b; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 const PRIMARY,b b 5 const 1 +1 SIMPLE t2 ref a a 5 const 2 Using where; Using index +DROP TABLE t1,t2; diff --git a/mysql-test/t/order_by.test b/mysql-test/t/order_by.test index 012b38ff8b7..15fb6771101 100644 --- a/mysql-test/t/order_by.test +++ b/mysql-test/t/order_by.test @@ -640,3 +640,16 @@ SELECT t2.b FROM t1 LEFT JOIN (t2, t3 LEFT JOIN t4 ON t3.a=t4.a) ON (t1.a=t2.a AND t1.b=t3.b) order by t2.b; DROP TABLE t1,t2,t3,t4; + +# +# BUG#16590: Optimized does not do right "const" table pre-read +# +CREATE TABLE t1 (a INT, b INT, PRIMARY KEY (a), UNIQUE KEY b (b)); +INSERT INTO t1 VALUES (1,1),(2,2); + +CREATE TABLE t2 (a INT, b INT, KEY a (a,b)); +INSERT INTO t2 VALUES (1,1),(1,2),(2,1),(2,2); + +EXPLAIN SELECT 1 FROM t1,t2 WHERE t1.b=2 AND t1.a=t2.a ORDER BY t2.b; + +DROP TABLE t1,t2; diff --git a/sql/sql_select.cc b/sql/sql_select.cc index c8830278e42..636b0d85c90 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -7722,6 +7722,22 @@ static void update_const_equal_items(COND *cond, JOIN_TAB *tab) key_map possible_keys= field->key_start; possible_keys.intersect(field->table->keys_in_use_for_query); stat[0].const_keys.merge(possible_keys); + + /* + For each field in the multiple equality (for which we know that it + is a constant) we have to find its corresponding key part, and set + that key part in const_key_parts. + */ + if (!possible_keys.is_clear_all()) + { + TABLE *tab= field->table; + KEYUSE *use; + for (use= stat->keyuse; use && use->table == tab; use++) + if (possible_keys.is_set(use->key) && + tab->key_info[use->key].key_part[use->keypart].field == + field) + tab->const_key_parts[use->key]|= use->keypart_map; + } } } }