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Commit a8c200c7 authored by Igor Babaev's avatar Igor Babaev
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MDEV-22042 Server crash in Item_field::print on ANALYZE FORMAT=JSON 

When processing a query with a recursive CTE a temporary table is used for
each recursive reference of the CTE. As any temporary table it uses its own
mem-root for table definition structures. Due to specifics of the current
implementation of ANALYZE stmt command this mem-root can be freed only at
the very of query processing. Such deallocation of mem-root memory happens
in close_thread_tables(). The function looks through the list of the tmp
tables rec_tables attached to the THD of the query and frees corresponding
mem-roots. If the query uses a stored function then such list is created
for each query of the function. When a new rec_list has to be created the
old one has to be saved and then restored at the proper moment.
The bug occurred because only one rec_list for the query containing CTE was
created. As a result close_thread_tables() freed tmp mem-roots used for
rec_tables prematurely destroying some data needed for the output produced
by the ANALYZE command.
parent fff7897e
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mysql-test/r/cte_recursive.result
View file @ a8c200c7
......@@ -3648,3 +3648,165 @@ select * from t1 as t;
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY t ALL NULL NULL NULL NULL 4
drop table t1,t2;
#
# MDEV-22042: ANALYZE of query using stored function and recursive CTE
#
create table t1 (a1 varchar(20),a2 varchar(20)) engine=myisam;
insert into t1 values (1,1),(2,2),(3,3);
create table t2 (
a2 varchar(20) primary key, b1 varchar(20), key (b1)
) engine=myisam;
insert into t2 values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7);
insert into t2 values (11,11),(12,12),(13,13),(14,14),(15,15),(16,16),(17,17);
create function f1(id varchar(20)) returns varchar(50)
begin
declare res varchar (50);
select a2 into res from t2 where a2=id and b1=1 limit 1;
return res;
end$$
select fv
from (select t1.a1, f1(t1.a2) fv from t1) dt
where (dt.a1) in (with recursive cte as (select a2 from t2 where a2='2'
union select tt2.a2 from t2 tt2 join cte on tt2.b1=cte.a2)
select a2 from cte);
fv
NULL
explain select fv
from (select t1.a1, f1(t1.a2) fv from t1) dt
where (dt.a1) in (with recursive cte as (select a2 from t2 where a2='2'
union select tt2.a2 from t2 tt2 join cte on tt2.b1=cte.a2)
select a2 from cte);
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY <subquery3> ALL distinct_key NULL NULL NULL 2
1 PRIMARY t1 ALL NULL NULL NULL NULL 3 Using where; Using join buffer (flat, BNL join)
3 MATERIALIZED <derived4> ALL NULL NULL NULL NULL 2
4 DERIVED t2 const PRIMARY PRIMARY 22 const 1 Using index
5 RECURSIVE UNION <derived4> ALL NULL NULL NULL NULL 2
5 RECURSIVE UNION tt2 ref b1 b1 23 cte.a2 2
NULL UNION RESULT <union4,5> ALL NULL NULL NULL NULL NULL
analyze format=json select fv
from (select t1.a1, f1(t1.a2) fv from t1) dt
where (dt.a1) in (with recursive cte as (select a2 from t2 where a2='2'
union select tt2.a2 from t2 tt2 join cte on tt2.b1=cte.a2)
select a2 from cte);
ANALYZE
{
"query_block": {
"select_id": 1,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "<subquery3>",
"access_type": "ALL",
"possible_keys": ["distinct_key"],
"r_loops": 1,
"rows": 2,
"r_rows": 1,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"materialized": {
"unique": 1,
"query_block": {
"select_id": 3,
"table": {
"table_name": "<derived4>",
"access_type": "ALL",
"r_loops": 1,
"rows": 2,
"r_rows": 1,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100,
"materialized": {
"query_block": {
"recursive_union": {
"table_name": "<union4,5>",
"access_type": "ALL",
"r_loops": 0,
"r_rows": null,
"query_specifications": [
{
"query_block": {
"select_id": 4,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "t2",
"access_type": "const",
"possible_keys": ["PRIMARY"],
"key": "PRIMARY",
"key_length": "22",
"used_key_parts": ["a2"],
"ref": ["const"],
"r_loops": 0,
"rows": 1,
"r_rows": null,
"filtered": 100,
"r_filtered": null,
"using_index": true
}
}
},
{
"query_block": {
"select_id": 5,
"r_loops": 1,
"r_total_time_ms": "REPLACED",
"table": {
"table_name": "<derived4>",
"access_type": "ALL",
"r_loops": 1,
"rows": 2,
"r_rows": 1,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100
},
"table": {
"table_name": "tt2",
"access_type": "ref",
"possible_keys": ["b1"],
"key": "b1",
"key_length": "23",
"used_key_parts": ["b1"],
"ref": ["cte.a2"],
"r_loops": 1,
"rows": 2,
"r_rows": 1,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100
}
}
}
]
}
}
}
}
}
}
},
"block-nl-join": {
"table": {
"table_name": "t1",
"access_type": "ALL",
"r_loops": 1,
"rows": 3,
"r_rows": 3,
"r_total_time_ms": "REPLACED",
"filtered": 100,
"r_filtered": 100
},
"buffer_type": "flat",
"buffer_size": "256Kb",
"join_type": "BNL",
"attached_condition": "t1.a1 = cte.a2",
"r_filtered": 33.333
}
}
}
drop function f1;
drop table t1,t2;
End of 10.2 tests
mysql-test/t/cte_recursive.test
View file @ a8c200c7
......@@ -2536,3 +2536,42 @@ with recursive cte as
select * from t1 as t;
drop table t1,t2;
--echo #
--echo # MDEV-22042: ANALYZE of query using stored function and recursive CTE
--echo #
create table t1 (a1 varchar(20),a2 varchar(20)) engine=myisam;
insert into t1 values (1,1),(2,2),(3,3);
create table t2 (
a2 varchar(20) primary key, b1 varchar(20), key (b1)
) engine=myisam;
insert into t2 values (1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7);
insert into t2 values (11,11),(12,12),(13,13),(14,14),(15,15),(16,16),(17,17);
delimiter $$;
create function f1(id varchar(20)) returns varchar(50)
begin
declare res varchar (50);
select a2 into res from t2 where a2=id and b1=1 limit 1;
return res;
end$$
delimiter ;$$
let q=
select fv
from (select t1.a1, f1(t1.a2) fv from t1) dt
where (dt.a1) in (with recursive cte as (select a2 from t2 where a2='2'
union select tt2.a2 from t2 tt2 join cte on tt2.b1=cte.a2)
select a2 from cte);
eval $q;
eval explain $q;
--source include/analyze-format.inc
eval analyze format=json $q;
drop function f1;
drop table t1,t2;
--echo End of 10.2 tests
sql/sp_head.cc
View file @ a8c200c7
......@@ -1126,6 +1126,7 @@ sp_head::execute(THD *thd, bool merge_da_on_success)
backup_arena;
query_id_t old_query_id;
TABLE *old_derived_tables;
TABLE *old_rec_tables;
LEX *old_lex;
Item_change_list old_change_list;
String old_packet;
......@@ -1201,6 +1202,8 @@ sp_head::execute(THD *thd, bool merge_da_on_success)
old_query_id= thd->query_id;
old_derived_tables= thd->derived_tables;
thd->derived_tables= 0;
old_rec_tables= thd->rec_tables;
thd->rec_tables= 0;
save_sql_mode= thd->variables.sql_mode;
thd->variables.sql_mode= m_sql_mode;
save_abort_on_warning= thd->abort_on_warning;
......@@ -1468,6 +1471,7 @@ sp_head::execute(THD *thd, bool merge_da_on_success)
thd->set_query_id(old_query_id);
DBUG_ASSERT(!thd->derived_tables);
thd->derived_tables= old_derived_tables;
thd->rec_tables= old_rec_tables;
thd->variables.sql_mode= save_sql_mode;
thd->abort_on_warning= save_abort_on_warning;
thd->m_reprepare_observer= save_reprepare_observer;
......
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