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Fixed mdev-15162 Query with CTE hangs if assignment operator (:=) is used

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If setting user variable was used in the specification of a recursive CTE
then Item_func_set_user_var::fix_fields() went into an infinite loop.
This commit is contained in:
Igor Babaev 2018-02-05 18:07:31 -08:00
parent 465979eabf
commit f271100836
3 changed files with 30 additions and 1 deletions
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13
mysql-test/r/cte_recursive.result
View File

@ -3079,3 +3079,16 @@ ERROR 21000: The used SELECT statements have a different number of columns
DROP TABLE a_tbl;
WITH RECURSIVE x AS (SELECT 1,2 UNION ALL SELECT 1 FROM x) SELECT * FROM x;
ERROR 21000: The used SELECT statements have a different number of columns
#
# MDEV-15162: Setting user variable in recursive CTE
#
SET @c=1;
WITH RECURSIVE cte AS
(SELECT 5
UNION
SELECT @c:=@c+1 FROM cte WHERE @c<3)
SELECT * FROM cte;
5
5
2
3

12
mysql-test/t/cte_recursive.test
View File

@ -2113,3 +2113,15 @@ DROP TABLE a_tbl;
--error ER_WRONG_NUMBER_OF_COLUMNS_IN_SELECT
WITH RECURSIVE x AS (SELECT 1,2 UNION ALL SELECT 1 FROM x) SELECT * FROM x;
--echo #
--echo # MDEV-15162: Setting user variable in recursive CTE
--echo #
SET @c=1;
WITH RECURSIVE cte AS
(SELECT 5
UNION
SELECT @c:=@c+1 FROM cte WHERE @c<3)
SELECT * FROM cte;

6
sql/item_func.cc
View File

@ -54,6 +54,7 @@
#include "set_var.h"
#include "debug_sync.h"
#include "sql_base.h"
#include "sql_cte.h"
#ifdef NO_EMBEDDED_ACCESS_CHECKS
#define sp_restore_security_context(A,B) while (0) {}
@ -4514,10 +4515,13 @@ bool Item_func_set_user_var::fix_fields(THD *thd, Item **ref)
TABLE_LIST *derived;
for (derived= unit->derived;
derived;
derived= derived->select_lex->master_unit()->derived)
derived= unit->derived)
{
derived->set_materialized_derived();
derived->prohibit_cond_pushdown= true;
if (unit->with_element && unit->with_element->is_recursive)
break;
unit= derived->select_lex->master_unit();
}
}