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  1. MariaDB Server
  2. MDEV-486

LP:1010116 - Incorrect query results in subqueries

Details

    • Bug
    • Status: Closed (View Workflow)
    • Minor
    • Resolution: Fixed
    • 5.5.25, 5.3.7
    • 5.5.27, 5.3.9
    • None

    Description

      https://bugs.launchpad.net/maria/+bug/1010116

      Test case 1 (with default optimizer_switch):

      SELECT
      		 
      `Derived1`.`id`,
      		 
      `Derived2`.`Val1`
      		 
      FROM (select 30631 as `id`) AS `Derived1` LEFT OUTER JOIN (SELECT
      		 
      2 as `id`,
      		 
      1 AS `Val1`
      		 
      FROM (select 30631 as `id`) AS `Derived3`) AS `Derived2` ON `Derived1`.`id` = `Derived2`.`id`;

      Expected result:

      id	Val1
      		 
      30631	NULL

      Actual result:

      id	Val1
      		 
      30631	1

      Reproducible on maria/5.3 revno 3562, maria/5.5 revno 3508
      Not reproducible on mysql/5.1 revno 3770, mysql/5.5 revno 3900, mysql/5.6 revno 3917, maria/5.2 revno 3168

      Test case 2

      create table t1 ( id int );
      		 
      insert into t1 values (30631);
      		 
      create table t2 ( id int );
      		 
      insert into t2 values (30631);
      		 
      create algorithm=MERGE view v2 as select 2 as id, 1 as val1 from t2;
      		 
      select t1.*, v2.* from t1 left join v2 on t1.id = v2.id;

      Expected result:

      id	id	val1
      		 
      30631	NULL	NULL

      Actual result:

      id	id	val1
      		 
      30631	2	1

      Reproducible on maria/5.2, maria/5.3, maria/5.5, mysql/5.1, mysql/5.5, mysql/5.6

      Attachments

        Issue Links

          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-3914 Wrong result (NULLs instead of real values) with INNER and RIGHT JOIN in a FROM subquery, derived_merge=on

          • Major - Major loss of function.
          • Closed

          Activity

            Ascending order - Click to sort in descending order
            sanja Oleksandr Byelkin added a comment -

            explain extended shows why result is incorrect (see constants in the select list in transformed query):

            Note 1003 select 30631 AS `id`,1 AS `Val1` from (select 30631 AS `id`) `Derived1` left join ((select 30631 AS `id`) `Derived3`) on(0) where 1
            select 30631 AS `id`,1 AS `Val1` from (select 30631 AS `id`) `Derived1` left join ((select 30631 AS `id`) `Derived3`) on(0) where 1;

            sanja Oleksandr Byelkin added a comment - explain extended shows why result is incorrect (see constants in the select list in transformed query): Note 1003 select 30631 AS `id`,1 AS `Val1` from (select 30631 AS `id`) `Derived1` left join ((select 30631 AS `id`) `Derived3`) on(0) where 1 select 30631 AS `id`,1 AS `Val1` from (select 30631 AS `id`) `Derived1` left join ((select 30631 AS `id`) `Derived3`) on(0) where 1;
            sanja Oleksandr Byelkin added a comment -

            substitution made during preparation (setup_fields).

            sanja Oleksandr Byelkin added a comment - substitution made during preparation (setup_fields).
            sanja Oleksandr Byelkin added a comment -

            Problem can be even expression over table fields (not only constants):
            create table t1 ( id int );
            insert into t1 values (30631);
            create table t2 ( id int );
            insert into t2 values (30631);
            create algorithm=MERGE view v2 as select 2 as id, id is null as bbb, 1 as val1 from t2;
            select t1., v2. from t1 left join v2 on t1.id = v2.id;

            drop view v2;
            drop table t1,t2;

            sanja Oleksandr Byelkin added a comment - Problem can be even expression over table fields (not only constants): create table t1 ( id int ); insert into t1 values (30631); create table t2 ( id int ); insert into t2 values (30631); create algorithm=MERGE view v2 as select 2 as id, id is null as bbb, 1 as val1 from t2; select t1. , v2. from t1 left join v2 on t1.id = v2.id; drop view v2; drop table t1,t2;
            sanja Oleksandr Byelkin added a comment -

            View variant also repeatable on 5.6 (probably earlier also).

            sanja Oleksandr Byelkin added a comment - View variant also repeatable on 5.6 (probably earlier also).
            serg Sergei Golubchik added a comment -

            repeatable on mysql-5.5 too

            serg Sergei Golubchik added a comment - repeatable on mysql-5.5 too
            sanja Oleksandr Byelkin added a comment -

            Patch committed, waiting for review...

            sanja Oleksandr Byelkin added a comment - Patch committed, waiting for review...
            serg Sergei Golubchik added a comment -

            pushed in 5.5

            serg Sergei Golubchik added a comment - pushed in 5.5

            People

              sanja Oleksandr Byelkin
              elenst Elena Stepanova
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              Dates

                Created:
                Updated:
                Resolved:

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