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MDEV-28602 Wrong result with outer join, merged derived table and view

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(Variant 3, initial variant was by Rex Jonston)

A LEFT JOIN with a constant as a column of the inner table produced wrong
query result if the optimizer had to write the inner table column into a
temp table. Query pattern:

  SELECT ...
  FROM (SELECT /*non-mergeable select*/
        FROM t1 LEFT JOIN (SELECT 'Y' as Val) t2 ON ...) as tbl

Fixed this by adding Item_direct_view_ref::save_in_field() which follows
the pattern of Item_direct_view_ref's save_org_in_field(),
save_in_result_field() and val_XXX() functions:
* call check_null_ref() and handle NULL value
* if we didn't get a NULL-complemented row, call Item_direct_ref's function.
This commit is contained in:
Sergei Petrunia
2023-01-04 13:01:47 +03:00
parent b218dfead2
commit b928c849d2
4 changed files with 263 additions and 0 deletions
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85
mysql-test/main/join_outer.test
View File

@ -6,6 +6,7 @@
--disable_warnings
drop table if exists t0,t1,t2,t3,t4,t5;
drop view if exists v0,v1,v2,v3;
--enable_warnings
SET @org_optimizer_switch=@@optimizer_switch;
@ -2341,6 +2342,90 @@ WHERE t3.pk IN (2);
drop view v4;
drop table t1,t2,t3,t4;
--echo #
--echo # MDEV-28602 Wrong result with outer join, merged derived table and view
--echo #
create table t1 (
Election int(10) unsigned NOT NULL
);
insert into t1 (Election) values (1);
create table t2 (
VoteID int(10),
ElectionID int(10),
UserID int(10)
);
insert into t2 (ElectionID, UserID) values (2, 30), (3, 30);
create view v1 as select * from t1
left join ( select 'Y' AS Voted, ElectionID from t2 ) AS T
on T.ElectionID = t1.Election
limit 9;
# limit X causes merge algorithm select as opposed to temp table
select * from v1;
drop table t1, t2;
drop view v1;
--echo #
--echo # and another contrived example showing a bit of heirarchy
--echo #
create table t10 (a int);
create table t20 (b int);
insert into t10 values (1),(2);
insert into t20 values (1),(3);
create view v10 as select *, 'U' as u from t10 left join (select 'Y' as y, t20.b from t20) dt1 on t10.a= dt1.b limit 3;
create table t30 (c int);
insert into t30 values (1),(3);
create view v20 as select * from t30 left join (select 'X' as x, v10.u, v10.y, v10.b from v10) dt2 on t30.c=dt2.b limit 6;
select * from v20 limit 9;
drop view v10, v20;
drop table t10, t20, t30;
--echo #
--echo # More complex testcase
--echo #
create table t2 (b int);
insert into t2 values (3),(7),(1);
create table t3 (c int);
insert into t3 values (3),(1);
create table t1 (a int);
insert into t1 values (1),(2),(7),(1);
select * from
(
select * from
(select 'Z' as z, t1.a from t1) dt1
left join
(select 'Y' as y, t2.b from t2) dt2
left join
(select 'X' as x, t3.c from t3) dt3
on dt2.b=dt3.c
on dt1.a=dt2.b
limit 9
) dt;
## Same as dt3 above
create view v3(x,c) as select * from (select 'X' as x, t3.c from t3) dt3;
## Same as dt2 above
create view v2(y,b) as select * from (select 'Y' as y, t2.b from t2) dt2;
## Same as (...) in the "... dt1 left join (...)" above
create view v0(y,b,x,c) as select * from v2 left join v3 on v2.b=v3.c;
# Same as above select statement
create view v1 as select 'Z' as z, t1.a, v0.* from t1 left join v0 on t1.a=v0.b limit 9;
select * from v1;
set statement join_cache_level=0 for
select * from v1;
drop view v0, v1, v2, v3;
drop table t1, t2, t3;
--echo # end of 10.3 tests
SET optimizer_switch=@org_optimizer_switch;