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MDEV-31226 Server crash or assertion failure with row size close to join_buffer_size

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The problem was that JOIN_CACHE::alloc_buffer() did not check if the
given join_buffer_value is less than the query require.

Added a check for this and disabled join cache if it cannot be used.
This commit is contained in:
Monty 2023-05-27 16:31:22 +03:00
parent 832b157bbe
commit d657f18ea7
3 changed files with 43 additions and 0 deletions
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23
mysql-test/main/join_cache.result
View File

@ -6233,3 +6233,26 @@ set @@optimizer_switch=@save_optimizer_switch;
set global innodb_stats_persistent= @innodb_stats_persistent_save; set global innodb_stats_persistent= @innodb_stats_persistent_save;
set global innodb_stats_persistent_sample_pages= set global innodb_stats_persistent_sample_pages=
@innodb_stats_persistent_sample_pages_save; @innodb_stats_persistent_sample_pages_save;
#
# MDEV-31226 Server crash or assertion failure with row size close to
# join_buffer_size
#
set @org_optimizer_switch=@@optimizer_switch;
set @org_join_buffer_size=@@join_buffer_size;
CREATE TABLE t (f VARCHAR(16384)) ENGINE=MyISAM CHARACTER SET utf8;
INSERT INTO t VALUES (REPEAT('a',16384)),(REPEAT('b',16384));
SET OPTIMIZER_SWITCH = 'optimize_join_buffer_size=off';
SET JOIN_BUFFER_SIZE = 16384;
explain SELECT length(concat(t1.f,t2.f)) FROM t t1, t t2;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 2
1 SIMPLE t2 ALL NULL NULL NULL NULL 2
SELECT length(concat(t1.f,t2.f)) FROM t t1, t t2;
length(concat(t1.f,t2.f))
32768
32768
32768
32768
DROP TABLE t;
set @@optimizer_switch=@org_optimizer_switch;
set @@join_buffer_size=@org_join_buffer_size;

17
mysql-test/main/join_cache.test
View File

@ -4207,3 +4207,20 @@ set @@optimizer_switch=@save_optimizer_switch;
set global innodb_stats_persistent= @innodb_stats_persistent_save; set global innodb_stats_persistent= @innodb_stats_persistent_save;
set global innodb_stats_persistent_sample_pages= set global innodb_stats_persistent_sample_pages=
@innodb_stats_persistent_sample_pages_save; @innodb_stats_persistent_sample_pages_save;
--echo #
--echo # MDEV-31226 Server crash or assertion failure with row size close to
--echo # join_buffer_size
--echo #
set @org_optimizer_switch=@@optimizer_switch;
set @org_join_buffer_size=@@join_buffer_size;
CREATE TABLE t (f VARCHAR(16384)) ENGINE=MyISAM CHARACTER SET utf8;
INSERT INTO t VALUES (REPEAT('a',16384)),(REPEAT('b',16384));
SET OPTIMIZER_SWITCH = 'optimize_join_buffer_size=off';
SET JOIN_BUFFER_SIZE = 16384;
explain SELECT length(concat(t1.f,t2.f)) FROM t t1, t t2;
SELECT length(concat(t1.f,t2.f)) FROM t t1, t t2;
DROP TABLE t;
set @@optimizer_switch=@org_optimizer_switch;
set @@join_buffer_size=@org_join_buffer_size;

3
sql/sql_join_cache.cc
View File

@ -945,6 +945,9 @@ int JOIN_CACHE::alloc_buffer()
join_buff_space_limit)) join_buff_space_limit))
goto fail; // Fatal error goto fail; // Fatal error
} }
else if (curr_min_buff_space_sz > buff_size)
goto fail;
if (for_explain_only) if (for_explain_only)
return 0; return 0;