From a405d30e93096175618f28ada9e0e8cb5f94b914 Mon Sep 17 00:00:00 2001 From: Sergey Glukhov Date: Wed, 19 Oct 2011 16:07:14 +0400 Subject: [PATCH] Bug#12540545 61101: ASSERTION FAILURE IN THREAD 1256741184 IN FILE /BUILDDIR/BUILD/BUILD/MYSQ The assertion in innodb is triggered in this way: 1. mysql server does lookup on the primary key with full key, innodb decides to not store cursor position because "any index_next/prev call will return EOF anyway" 2. server asks innodb to return any next record in the index and the assertion is triggered because no cursor position is stored. It happens when a unique search (match_mode=ROW_SEL_EXACT) in the clustered index is performed. InnoDB has never stored the cursor position after a unique key lookup in the clustered index because storing the position is an expensive operation. The bug was introduced by WL3220 'Loose index scan for aggregate functions'. The fix is to disallow loose index scan optimization for AGG_FUNC(DISTINCT ...) if GROUP_MIN_MAX quick select uses clustered key. mysql-test/r/group_min_max_innodb.result: test case mysql-test/t/group_min_max_innodb.test: test case sql/opt_range.cc: disallow loose index scan optimization for AGG_FUNC(DISTINCT ...) if GROUP_MIN_MAX quick select uses clustered key. --- mysql-test/r/group_min_max_innodb.result | 24 ++++++++++++++++++++++++ mysql-test/t/group_min_max_innodb.test | 20 ++++++++++++++++++++ sql/opt_range.cc | 12 ++++++++++++ 3 files changed, 56 insertions(+) diff --git a/mysql-test/r/group_min_max_innodb.result b/mysql-test/r/group_min_max_innodb.result index 6607e1babf6..0e7841e979d 100644 --- a/mysql-test/r/group_min_max_innodb.result +++ b/mysql-test/r/group_min_max_innodb.result @@ -94,3 +94,27 @@ pk drop view v1; drop table t1; End of 5.1 tests +# +# Bug#12540545 61101: ASSERTION FAILURE IN THREAD 1256741184 IN +# FILE /BUILDDIR/BUILD/BUILD/MYSQ +# +CREATE TABLE t1 (a CHAR(1), b CHAR(1), PRIMARY KEY (a,b)) ENGINE=InnoDB; +INSERT INTO t1 VALUES ('a', 'b'), ('c', 'd'); +EXPLAIN SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 index NULL PRIMARY 2 NULL 2 Using where; Using index +SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +COUNT(DISTINCT a) +1 +DROP TABLE t1; +CREATE TABLE t1 (a CHAR(1) NOT NULL, b CHAR(1) NOT NULL, UNIQUE KEY (a,b)) +ENGINE=InnoDB; +INSERT INTO t1 VALUES ('a', 'b'), ('c', 'd'); +EXPLAIN SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +id select_type table type possible_keys key key_len ref rows Extra +1 SIMPLE t1 index NULL a 2 NULL 2 Using where; Using index +SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +COUNT(DISTINCT a) +1 +DROP TABLE t1; +End of 5.5 tests diff --git a/mysql-test/t/group_min_max_innodb.test b/mysql-test/t/group_min_max_innodb.test index 643b4f7d55e..7038eb2ff47 100644 --- a/mysql-test/t/group_min_max_innodb.test +++ b/mysql-test/t/group_min_max_innodb.test @@ -117,3 +117,23 @@ drop view v1; drop table t1; --echo End of 5.1 tests + +--echo # +--echo # Bug#12540545 61101: ASSERTION FAILURE IN THREAD 1256741184 IN +--echo # FILE /BUILDDIR/BUILD/BUILD/MYSQ +--echo # + +CREATE TABLE t1 (a CHAR(1), b CHAR(1), PRIMARY KEY (a,b)) ENGINE=InnoDB; +INSERT INTO t1 VALUES ('a', 'b'), ('c', 'd'); +EXPLAIN SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +DROP TABLE t1; + +CREATE TABLE t1 (a CHAR(1) NOT NULL, b CHAR(1) NOT NULL, UNIQUE KEY (a,b)) +ENGINE=InnoDB; +INSERT INTO t1 VALUES ('a', 'b'), ('c', 'd'); +EXPLAIN SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +SELECT COUNT(DISTINCT a) FROM t1 WHERE b = 'b'; +DROP TABLE t1; + +--echo End of 5.5 tests diff --git a/sql/opt_range.cc b/sql/opt_range.cc index 730024f4389..8a6607cf343 100644 --- a/sql/opt_range.cc +++ b/sql/opt_range.cc @@ -9318,6 +9318,11 @@ cost_group_min_max(TABLE* table, KEY *index_info, uint used_key_parts, except MIN and MAX. For queries with DISTINCT, aggregate functions are allowed. SA5. The select list in DISTINCT queries should not contain expressions. + SA6. Clustered index can not be used by GROUP_MIN_MAX quick select + for AGG_FUNC(DISTINCT ...) optimization because cursor position is + never stored after a unique key lookup in the clustered index and + furhter index_next/prev calls can not be used. So loose index scan + optimization can not be used in this case. GA1. If Q has a GROUP BY clause, then GA is a prefix of I. That is, if G_i = A_j => i = j. GA2. If Q has a DISTINCT clause, then there is a permutation of SA that @@ -9804,6 +9809,13 @@ get_best_group_min_max(PARAM *param, SEL_TREE *tree, double read_time) Field::itMBR : Field::itRAW)) DBUG_RETURN(NULL); + /* + Check (SA6) if clustered key is used + */ + if (is_agg_distinct && index == table->s->primary_key && + table->file->primary_key_is_clustered()) + DBUG_RETURN(NULL); + /* The query passes all tests, so construct a new TRP object. */ read_plan= new (param->mem_root) TRP_GROUP_MIN_MAX(have_min, have_max, is_agg_distinct,