database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-08-01 03:47:19 +03:00
Code Activity

MDEV-3928: Assertion `example' failed in Item_cache::is_expensive_processor with a 2-level IN subquery

Browse Source 
Analysis:
The following call stack shows that it is possible to set Item_cache::value_cached, and the relevant value
without setting Item_cache::example.

#0 Item_cache_temporal::store_packed at item.cc:8395
#1 get_datetime_value at item_cmpfunc.cc:915
#2 resolve_const_item at item.cc:7987
#3 propagate_cond_constants at sql_select.cc:12264
#4 propagate_cond_constants at sql_select.cc:12227
#5 optimize_cond at sql_select.cc:13026
#6 JOIN::optimize at sql_select.cc:1016
#7 st_select_lex::optimize_unflattened_subqueries at sql_lex.cc:3161
#8 JOIN::optimize_unflattened_subqueries at opt_subselect.cc:4880
#9 JOIN::optimize at sql_select.cc:1554

The fix is to set Item_cache_temporal::example even when the value is
set directly by Item_cache_temporal::store_packed. This makes the
Item_cache_temporal object consistent.
This commit is contained in:
unknown
2012-12-19 15:56:57 +02:00
parent 0aad592f49
commit e99aa91e90
5 changed files with 59 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
mysql-test/r/subselect4.result
View File

@ -2279,5 +2279,31 @@ MAX(a) bb
NULL NULL
drop table t1, t2;
set optimizer_switch=@subselect4_tmp;
#
# MDEV-3928 Assertion `example' failed in Item_cache::is_expensive_processor with a 2-level IN subquery
#
CREATE TABLE t1 (a1 INT, b1 TIME) ENGINE=MyISAM;
INSERT INTO t1 VALUES (4,'21:22:34'),(6,'10:50:38');
CREATE TABLE t2 (a2 INT, b2 TIME) ENGINE=MyISAM;
INSERT INTO t2 VALUES (8, '06:17:39');
CREATE TABLE t3 (a3 INT, b3 TIME) ENGINE=MyISAM;
INSERT INTO t3 VALUES (1,'00:00:01'),(7,'00:00:02');
EXPLAIN
SELECT * FROM t1 WHERE a1 IN (
SELECT a2 FROM t2 WHERE a2 IN (
SELECT a3 FROM t3 WHERE b2 = b1 AND b2 <= b1 ORDER BY b3
)
);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t2 system NULL NULL NULL NULL 1
1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
3 DEPENDENT SUBQUERY t3 ALL NULL NULL NULL NULL 2 Using where
SELECT * FROM t1 WHERE a1 IN (
SELECT a2 FROM t2 WHERE a2 IN (
SELECT a3 FROM t3 WHERE b2 = b1 AND b2 <= b1 ORDER BY b3
)
);
a1 b1
drop table t1, t2, t3;
SET optimizer_switch= @@global.optimizer_switch;
set @@tmp_table_size= @@global.tmp_table_size;

28
mysql-test/t/subselect4.test
View File

@ -1858,5 +1858,33 @@ drop table t1, t2;
set optimizer_switch=@subselect4_tmp;
--echo #
--echo # MDEV-3928 Assertion `example' failed in Item_cache::is_expensive_processor with a 2-level IN subquery
--echo #
CREATE TABLE t1 (a1 INT, b1 TIME) ENGINE=MyISAM;
INSERT INTO t1 VALUES (4,'21:22:34'),(6,'10:50:38');
CREATE TABLE t2 (a2 INT, b2 TIME) ENGINE=MyISAM;
INSERT INTO t2 VALUES (8, '06:17:39');
CREATE TABLE t3 (a3 INT, b3 TIME) ENGINE=MyISAM;
INSERT INTO t3 VALUES (1,'00:00:01'),(7,'00:00:02');
EXPLAIN
SELECT * FROM t1 WHERE a1 IN (
SELECT a2 FROM t2 WHERE a2 IN (
SELECT a3 FROM t3 WHERE b2 = b1 AND b2 <= b1 ORDER BY b3
)
);
SELECT * FROM t1 WHERE a1 IN (
SELECT a2 FROM t2 WHERE a2 IN (
SELECT a3 FROM t3 WHERE b2 = b1 AND b2 <= b1 ORDER BY b3
)
);
drop table t1, t2, t3;
SET optimizer_switch= @@global.optimizer_switch;
set @@tmp_table_size= @@global.tmp_table_size;

3
sql/item.cc
View File

@ -8388,9 +8388,10 @@ int Item_cache_temporal::save_in_field(Field *field, bool no_conversions)
}
void Item_cache_temporal::store_packed(longlong val_arg)
void Item_cache_temporal::store_packed(longlong val_arg, Item *example)
{
/* An explicit values is given, save it. */
store(example);
value_cached= true;
value= val_arg;
null_value= false;

4
sql/item.h
View File

@ -3799,7 +3799,7 @@ public:
bool cache_value();
bool get_date(MYSQL_TIME *ltime, uint fuzzydate);
int save_in_field(Field *field, bool no_conversions);
void store_packed(longlong val_arg);
void store_packed(longlong val_arg, Item *example);
/*
Having a clone_item method tells optimizer that this object
is a constant and need not be optimized further.
@ -3808,7 +3808,7 @@ public:
Item *clone_item()
{
Item_cache_temporal *item= new Item_cache_temporal(cached_field_type);
item->store_packed(value);
item->store_packed(value, example);
return item;
}
};

2
sql/item_cmpfunc.cc
View File

@ -912,7 +912,7 @@ get_datetime_value(THD *thd, Item ***item_arg, Item **cache_arg,
if (save_arena)
thd->set_query_arena(save_arena);
cache->store_packed(value);
cache->store_packed(value, item);
*cache_arg= cache;
*item_arg= cache_arg;
}