From 926edd48e1e67bf9a315b3602638a76c4c445ef6 Mon Sep 17 00:00:00 2001 From: Varun Gupta Date: Tue, 6 Mar 2018 19:59:57 +0530 Subject: [PATCH] MDEV-15235: Assertion `length > 0' failed in create_ref_for_key The issue is that we are creating a materialised table with key of length 0 which is incorrect, we should disable materialisation for such a case. --- mysql-test/r/subselect_mat.result | 15 +++++++++++++++ mysql-test/t/subselect_mat.test | 13 +++++++++++++ sql/opt_subselect.cc | 4 +++- 3 files changed, 31 insertions(+), 1 deletion(-) diff --git a/mysql-test/r/subselect_mat.result b/mysql-test/r/subselect_mat.result index d4dc519227b14..00448ac4f9135 100644 --- a/mysql-test/r/subselect_mat.result +++ b/mysql-test/r/subselect_mat.result @@ -2642,3 +2642,18 @@ a b sq 4 4 1 4 2 1 drop table t1, t2; +# +# MDEV-15235: Assertion `length > 0' failed in create_ref_for_key +# +CREATE TABLE t1 (i INT); +INSERT INTO t1 VALUES (1),(2); +CREATE TABLE t2 (f CHAR(1)); +INSERT INTO t2 VALUES ('a'),('b'); +explain +SELECT * FROM t2 WHERE f IN ( SELECT LEFT('foo',0) FROM t1 ORDER BY 1 ); +id select_type table type possible_keys key key_len ref rows Extra +1 PRIMARY t2 ALL NULL NULL NULL NULL 2 Using where +2 DEPENDENT SUBQUERY t1 ALL NULL NULL NULL NULL 2 +SELECT * FROM t2 WHERE f IN ( SELECT LEFT('foo',0) FROM t1 ORDER BY 1 ); +f +DROP TABLE t1, t2; diff --git a/mysql-test/t/subselect_mat.test b/mysql-test/t/subselect_mat.test index 09c6b3e1747bc..5211f35b48b02 100644 --- a/mysql-test/t/subselect_mat.test +++ b/mysql-test/t/subselect_mat.test @@ -254,3 +254,16 @@ SELECT a, b, (a, b) NOT IN (SELECT a, b FROM t2) as sq FROM t1; drop table t1, t2; + +--echo # +--echo # MDEV-15235: Assertion `length > 0' failed in create_ref_for_key +--echo # + +CREATE TABLE t1 (i INT); +INSERT INTO t1 VALUES (1),(2); +CREATE TABLE t2 (f CHAR(1)); +INSERT INTO t2 VALUES ('a'),('b'); +explain +SELECT * FROM t2 WHERE f IN ( SELECT LEFT('foo',0) FROM t1 ORDER BY 1 ); +SELECT * FROM t2 WHERE f IN ( SELECT LEFT('foo',0) FROM t1 ORDER BY 1 ); +DROP TABLE t1, t2; diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc index 028bf44bf79e4..24f35a0c14c92 100644 --- a/sql/opt_subselect.cc +++ b/sql/opt_subselect.cc @@ -873,8 +873,10 @@ bool subquery_types_allow_materialization(Item_in_subselect *in_subs) Make sure that create_tmp_table will not fail due to too long keys. See MDEV-7122. This check is performed inside create_tmp_table also and we must do it so that we know the table has keys created. + Make sure that the length of the key for the temp_table is atleast + greater than 0. */ - if (total_key_length > tmp_table_max_key_length() || + if (!total_key_length || total_key_length > tmp_table_max_key_length() || elements > tmp_table_max_key_parts()) DBUG_RETURN(FALSE);