maria-developers team mailing list archive

["Philip Stoev" <pstoev@xxxxxxxxxxxx>]

ok, I am on it.

----- Original Message ----- 
From: "Sergey Petrunya" <psergey@xxxxxxxxxxxx>
To: "Philip Stoev" <pstoev@xxxxxxxxxxxx>
Cc: <maria-developers@xxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, June 28, 2011 9:26 AM
Subject: Philip please test: Duplicate Elimination for outer joins + 
semijoins


> Hello Philip,
>
> I'd like to get the tree at lp:~maria-captains/maria/5.3-subqueries-mwl90
> tested for Duplicate Elimination with outer+semi-join processing.
>
> I'm interested in crashes, as well as wrong query result bugs. The code 
> path
> that needs to be tested is selected with this @@optimizer_switch setting:
>
>  semijoin=on,materialization=off,firstmatch=off,loosescan=off
>
> this set of switches disables all semi-join subquery strategies except
> DuplicateElimination, so you should have no problem with hitting the
>
> If you also set "semijoin=off" then you get the execution path that we 
> assume
> will always produce correct results.
>
> Query pattern
>
>  SELECT .... FROM complex_join
>  WHERE
>    top_where AND (SELECT ... FROM complex_join WHERE ...)
>
> where
> - subqueries must be "mergeable semi-joins":
>    = no aggregates, unions, or ORDER BYs
> - both correlated and ucorrelated subqueries are OK.
> - complex_join is arbitrary join structure (comma join, "t1 JOIN t2", 
> various
>   kinds of outer joins - everything should work)
>
> - multiple sibling subqueries, as well as nested subqueries are covered by
>   what you're testing.
>
> EXPLAIN
> - Should have id=='1' && select_type='PRIMARY' on all lines.
> - Should use Start Temporary/End temporary.
>
> BR
> Sergey
> --
> Sergey Petrunia, Software Developer
> Monty Program AB, http://askmonty.org
> Blog: http://s.petrunia.net/blog