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MDEV-10080 Derived tables allow double LIMIT clause

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1. Moving the "| get_select_lex_derived select_derived_init" part of
select_derived into a separate new rule derived_query_specification.
2. Using derived_query_specification directly in select_derived_union
rather than in select_derived.
3. Moving the sequence "opt_order_clause opt_limit_clause opt_select_lock_type"
from select_derived2 to select_derived_union,
after derived_query_specification.

Effectively, the parser now does not go through the sequence
"opt_order_clause opt_limit_clause ... opt_union_order_or_limit" any more.

This fixes the problem with double LIMIT clause and removes 2 shift/reduce
conflicts.
This commit is contained in:
Alexander Barkov
2016-05-20 09:21:07 +04:00
parent c9629daa1e
commit f6a7c1c75a
3 changed files with 35 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
mysql-test/r/parser.result
View File

@ -840,7 +840,7 @@ ERROR 42000: You have an error in your SQL syntax; check the manual that corresp
SELECT (SELECT 1 FROM t1 LIMIT 1 ORDER BY 1 UNION SELECT 1 FROM t1);
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'ORDER BY 1 UNION SELECT 1 FROM t1)' at line 1
SELECT 1 FROM (SELECT 1 FROM t1 LIMIT 1 ORDER BY 1 UNION SELECT 1 FROM t1) a;
ERROR HY000: Incorrect usage of UNION and ORDER BY
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'ORDER BY 1 UNION SELECT 1 FROM t1) a' at line 1
SELECT 1 FROM t1 ORDER BY 1 UNION SELECT 1 FROM t1 ORDER BY 1;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'UNION SELECT 1 FROM t1 ORDER BY 1' at line 1
SELECT (SELECT 1 FROM t1 ORDER BY 1 UNION SELECT 1 FROM t1 ORDER BY 1);
@ -878,3 +878,11 @@ a
2
1
DROP TABLE t1;
#
# MDEV-10080 Derived tables allow double LIMIT clause
#
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2),(3);
SELECT * FROM (SELECT * FROM t1 LIMIT 1 LIMIT 2) t1;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'LIMIT 2) t1' at line 1
DROP TABLE t1;

11
mysql-test/t/parser.test
View File

@ -975,7 +975,7 @@ let $q=SELECT 1 FROM t1 LIMIT 1 ORDER BY 1 UNION SELECT 1 FROM t1;
eval $q;
--error ER_PARSE_ERROR
eval SELECT ($q);
--error ER_WRONG_USAGE
--error ER_PARSE_ERROR
eval SELECT 1 FROM ($q) a;
let $q=SELECT 1 FROM t1 ORDER BY 1 UNION SELECT 1 FROM t1 ORDER BY 1;
@ -1021,3 +1021,12 @@ SELECT *
FROM ( (SELECT a FROM t1 ORDER BY a) UNION (SELECT 1 as b ORDER BY b ) ) AS a1
WHERE a1.a = 1 OR a1.a = 2;
DROP TABLE t1;
--echo #
--echo # MDEV-10080 Derived tables allow double LIMIT clause
--echo #
CREATE TABLE t1 (a INT);
INSERT INTO t1 VALUES (1),(2),(3);
--error ER_PARSE_ERROR
SELECT * FROM (SELECT * FROM t1 LIMIT 1 LIMIT 2) t1;
DROP TABLE t1;

23
sql/sql_yacc.yy
View File

@ -1037,10 +1037,10 @@ bool my_yyoverflow(short **a, YYSTYPE **b, ulong *yystacksize);
%parse-param { THD *thd }
%lex-param { THD *thd }
/*
Currently there are 104 shift/reduce conflicts.
Currently there are 102 shift/reduce conflicts.
We should not introduce new conflicts any more.
*/
%expect 104
%expect 102
/*
Comments for TOKENS.
@ -11121,6 +11121,11 @@ select_derived_union:
MYSQL_YYABORT;
}
}
| derived_query_specification
opt_order_clause
opt_limit_clause
opt_select_lock_type
{ $$= NULL; }
| select_derived_union union_head_non_top query_term
{
/*
@ -11181,7 +11186,15 @@ select_derived:
MYSQL_YYABORT;
}
}
| get_select_lex_derived select_derived_init
;
/*
Similar to query_specification, but for derived tables.
Example: the inner parenthesized SELECT in this query:
SELECT * FROM (SELECT * FROM t1);
*/
derived_query_specification:
get_select_lex_derived select_derived_init
{
// Now we have the same st_select_lex that we had in the beginning
DBUG_ASSERT($1 == Lex->current_select);
@ -11198,7 +11211,6 @@ select_derived:
MYSQL_YYABORT;
}
}
$$= NULL;
}
;
@ -11224,9 +11236,6 @@ select_derived2:
Select->parsing_place= NO_MATTER;
}
opt_table_expression
opt_order_clause
opt_limit_clause
opt_select_lock_type
;
get_select_lex: