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MDEV-19363 Assertion `select_lex' failed in LEX::pop_select

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This patch corrects the patch for MDEV-19324. The latter did not
work properly in the cases when the transformation
  (SELECT ... ORDER BY ...) LIMIT ... =>
   SELECT ... ORDER BY ... LIMIT ...
was applied to the operands of a set operation.
This commit is contained in:
Igor Babaev 2019-05-01 18:20:06 -07:00
parent ea679c88c3
commit 2b7e080fae
3 changed files with 79 additions and 3 deletions
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59
mysql-test/main/brackets.result
View file

@ -393,4 +393,63 @@ EXPLAIN
}
}
drop table t1;
#
# MDEV-19363: ((SELECT ...) ORDER BY col ) LIMIT n UNION ...
#
create table t1 (pk int);
insert into t1 values (5),(4),(1),(2),(3);
((select * from t1 order by pk) limit 2) union (select * from t1 where pk > 4);
pk
1
2
5
explain extended ((select * from t1 order by pk) limit 2) union (select * from t1 where pk > 4);
id select_type table type possible_keys key key_len ref rows filtered Extra
1 PRIMARY t1 ALL NULL NULL NULL NULL 5 100.00 Using filesort
2 UNION t1 ALL NULL NULL NULL NULL 5 100.00 Using where
NULL UNION RESULT <union1,2> ALL NULL NULL NULL NULL NULL NULL
Warnings:
Note 1003 (/* select#1 */ select `test`.`t1`.`pk` AS `pk` from `test`.`t1` order by `test`.`t1`.`pk` limit 2) union (/* select#2 */ select `test`.`t1`.`pk` AS `pk` from `test`.`t1` where `test`.`t1`.`pk` > 4)
explain format=json ((select * from t1 order by pk) limit 2) union (select * from t1 where pk > 4);
EXPLAIN
{
"query_block": {
"union_result": {
"table_name": "<union1,2>",
"access_type": "ALL",
"query_specifications": [
{
"query_block": {
"select_id": 1,
"read_sorted_file": {
"filesort": {
"sort_key": "t1.pk",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 5,
"filtered": 100
}
}
}
}
},
{
"query_block": {
"select_id": 2,
"operation": "UNION",
"table": {
"table_name": "t1",
"access_type": "ALL",
"rows": 5,
"filtered": 100,
"attached_condition": "t1.pk > 4"
}
}
}
]
}
}
}
drop table t1;
# End of 10.4 tests

15
mysql-test/main/brackets.test
View file

@ -139,5 +139,20 @@ eval explain format=json $q2;
drop table t1;
--echo #
--echo # MDEV-19363: ((SELECT ...) ORDER BY col ) LIMIT n UNION ...
--echo #
create table t1 (pk int);
insert into t1 values (5),(4),(1),(2),(3);
let $q=
((select * from t1 order by pk) limit 2) union (select * from t1 where pk > 4);
eval $q;
eval explain extended $q;
eval explain format=json $q;
drop table t1;
--echo # End of 10.4 tests

8
sql/sql_lex.cc
View file

@ -9147,13 +9147,15 @@ SELECT_LEX *LEX::parsed_select(SELECT_LEX *sel, Lex_order_limit_lock * l)
}
else
{
SELECT_LEX_UNIT *unit= create_unit(sel);
if (!unit)
return NULL;
if (!l->order_list && !sel->explicit_limit)
l->order_list= &sel->order_list;
else
{
SELECT_LEX_UNIT *unit= create_unit(sel);
if (!unit)
return NULL;
sel= wrap_unit_into_derived(unit);
}
if (!sel)
return NULL;
l->set_to(sel);