revision-id: 6a04c2a1aa60e67c07d4e6ada63f65cc3b26a5a9 (mariadb-5.5.60-13-g6a04c2a) parent(s): 27a7365f42ce0184a004e09b3bb1cadb868c8f64 author: Igor Babaev committer: Igor Babaev timestamp: 2018-05-22 12:09:05 -0700 message: MDEV-16235 Server crashes in my_utf8_uni or in my_strtod_int upon SELECT .. LIMIT 0 The code must differentiate between a SELECT with contradictory WHERE/HAVING and one with LIMIT 0. Also for the latter printed 'Zero limit' instead of 'Impossible where' in the EXPLAIN output. --- mysql-test/r/limit.result | 16 ++++++++++++++++ mysql-test/r/subselect4.result | 2 +- mysql-test/r/subselect_mat_cost_bugs.result | 2 +- mysql-test/t/limit.test | 14 ++++++++++++++ mysql-test/t/subselect4.test | 2 +- sql/sql_select.cc | 17 +++++++++++++---- 6 files changed, 46 insertions(+), 7 deletions(-) diff --git a/mysql-test/r/limit.result b/mysql-test/r/limit.result index 176a93c..deb4ca2 100644 --- a/mysql-test/r/limit.result +++ b/mysql-test/r/limit.result @@ -146,3 +146,19 @@ a 16 DROP TABLE t1; End of 5.1 tests +# +# mdev-16235: SELECT over a table with LIMIT 0 +# +EXPLAIN +SELECT * FROM mysql.slow_log WHERE sql_text != 'foo' LIMIT 0; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Zero limit +SELECT * FROM mysql.slow_log WHERE sql_text != 'foo' LIMIT 0; +start_time user_host query_time lock_time rows_sent rows_examined db last_insert_id insert_id server_id sql_text +EXPLAIN +SELECT * FROM mysql.help_topic WHERE help_category_id != example LIMIT 0; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Zero limit +SELECT * FROM mysql.help_topic WHERE help_category_id != example LIMIT 0; +help_topic_id name help_category_id description example url +End of 5.5 tests diff --git a/mysql-test/r/subselect4.result b/mysql-test/r/subselect4.result index 6accc23..8973330 100644 --- a/mysql-test/r/subselect4.result +++ b/mysql-test/r/subselect4.result @@ -2512,7 +2512,7 @@ SELECT 2 IN (SELECT 2 from DUAL WHERE 1 != 1); SET optimizer_switch= @@global.optimizer_switch; set @@tmp_table_size= @@global.tmp_table_size; # -# mfrv-14515: Wrong results for tableless query with subquery in WHERE +# mdev-14515: Wrong results for tableless query with subquery in WHERE # and implicit aggregation # create table t1 (i1 int, i2 int); diff --git a/mysql-test/r/subselect_mat_cost_bugs.result b/mysql-test/r/subselect_mat_cost_bugs.result index df6b543..d33f148 100644 --- a/mysql-test/r/subselect_mat_cost_bugs.result +++ b/mysql-test/r/subselect_mat_cost_bugs.result @@ -334,7 +334,7 @@ SELECT * FROM t1 WHERE (f1) IN (SELECT f1 FROM t2) LIMIT 0; id select_type table type possible_keys key key_len ref rows Extra -1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE +1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Zero limit 2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where SELECT * FROM t1 WHERE (f1) IN (SELECT f1 FROM t2) diff --git a/mysql-test/t/limit.test b/mysql-test/t/limit.test index 4dbe130..668d3b7 100644 --- a/mysql-test/t/limit.test +++ b/mysql-test/t/limit.test @@ -115,3 +115,17 @@ SELECT a FROM t1 ORDER BY a LIMIT 2 OFFSET 14; DROP TABLE t1; --echo End of 5.1 tests + +--echo # +--echo # mdev-16235: SELECT over a table with LIMIT 0 +--echo # + +EXPLAIN +SELECT * FROM mysql.slow_log WHERE sql_text != 'foo' LIMIT 0; +SELECT * FROM mysql.slow_log WHERE sql_text != 'foo' LIMIT 0; + +EXPLAIN +SELECT * FROM mysql.help_topic WHERE help_category_id != example LIMIT 0; +SELECT * FROM mysql.help_topic WHERE help_category_id != example LIMIT 0; + +--echo End of 5.5 tests diff --git a/mysql-test/t/subselect4.test b/mysql-test/t/subselect4.test index 2b53b55..2727fd9 100644 --- a/mysql-test/t/subselect4.test +++ b/mysql-test/t/subselect4.test @@ -2047,7 +2047,7 @@ SET optimizer_switch= @@global.optimizer_switch; set @@tmp_table_size= @@global.tmp_table_size; --echo # ---echo # mfrv-14515: Wrong results for tableless query with subquery in WHERE +--echo # mdev-14515: Wrong results for tableless query with subquery in WHERE --echo # and implicit aggregation --echo # diff --git a/sql/sql_select.cc b/sql/sql_select.cc index 1e9f1c0..d6d269a 100644 --- a/sql/sql_select.cc +++ b/sql/sql_select.cc @@ -1136,10 +1136,19 @@ JOIN::optimize() if (cond_value == Item::COND_FALSE || having_value == Item::COND_FALSE || (!unit->select_limit_cnt && !(select_options & OPTION_FOUND_ROWS))) { /* Impossible cond */ - DBUG_PRINT("info", (having_value == Item::COND_FALSE ? - "Impossible HAVING" : "Impossible WHERE")); - zero_result_cause= having_value == Item::COND_FALSE ? - "Impossible HAVING" : "Impossible WHERE"; + if (unit->select_limit_cnt) + { + DBUG_PRINT("info", (having_value == Item::COND_FALSE ? + "Impossible HAVING" : "Impossible WHERE")); + zero_result_cause= having_value == Item::COND_FALSE ? + "Impossible HAVING" : "Impossible WHERE"; + } + else + { + DBUG_PRINT("info", ("Zero limit")); + zero_result_cause= "Zero limit"; + conds= 0; + } table_count= top_join_tab_count= 0; error= 0; goto setup_subq_exit;