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MDEV-19956 Queries with subqueries containing UNION are not parsed

Shift-Reduce conflicts prevented parsing some queries with subqueries that
used set operations when the subqueries occurred in expressions or in IN
predicands.
The grammar rules for query expression were transformed in order to avoid
these conflicts. New grammar rules employ an idea taken from MySQL 8.0.
This commit is contained in:
Igor Babaev
2019-09-20 09:03:38 -07:00
parent e3da362c03
commit b44171428a
21 changed files with 7212 additions and 593 deletions

View File

@ -25,7 +25,7 @@ id select_type table type possible_keys key key_len ref rows filtered Extra
3 EXCEPT t2 ALL NULL NULL NULL NULL 2 100.00
NULL EXCEPT RESULT <except2,3> ALL NULL NULL NULL NULL NULL NULL
Warnings:
Note 1003 /* select#1 */ select `a`.`a` AS `a`,`a`.`b` AS `b` from (/* select#2 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` except (/* select#3 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2`)) `a`
Note 1003 /* select#1 */ select `a`.`a` AS `a`,`a`.`b` AS `b` from ((/* select#2 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1`) except (/* select#3 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d` from `test`.`t2`)) `a`
EXPLAIN format=json (select a,b from t1) except (select c,d from t2);
EXPLAIN
{
@ -230,7 +230,7 @@ id select_type table type possible_keys key key_len ref rows filtered Extra
3 EXCEPT t4 ALL NULL NULL NULL NULL 2 100.00 Using join buffer (flat, BNL join)
NULL EXCEPT RESULT <except2,3> ALL NULL NULL NULL NULL NULL NULL
Warnings:
Note 1003 /* select#1 */ select `a`.`a` AS `a`,`a`.`b` AS `b`,`a`.`e` AS `e`,`a`.`f` AS `f` from (/* select#2 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t3`.`e` AS `e`,`test`.`t3`.`f` AS `f` from `test`.`t1` join `test`.`t3` except (/* select#3 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d`,`test`.`t4`.`g` AS `g`,`test`.`t4`.`h` AS `h` from `test`.`t2` join `test`.`t4`)) `a`
Note 1003 /* select#1 */ select `a`.`a` AS `a`,`a`.`b` AS `b`,`a`.`e` AS `e`,`a`.`f` AS `f` from ((/* select#2 */ select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t3`.`e` AS `e`,`test`.`t3`.`f` AS `f` from `test`.`t1` join `test`.`t3`) except (/* select#3 */ select `test`.`t2`.`c` AS `c`,`test`.`t2`.`d` AS `d`,`test`.`t4`.`g` AS `g`,`test`.`t4`.`h` AS `h` from `test`.`t2` join `test`.`t4`)) `a`
EXPLAIN format=json (select a,b,e,f from t1,t3) except (select c,d,g,h from t2,t4);
EXPLAIN
{