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Re: Philip please test: Duplicate Elimination for outer joins + semijoins


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:


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
   top_where AND (SELECT ... FROM complex_join 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.

- Should have id=='1' && select_type='PRIMARY' on all lines.
- Should use Start Temporary/End temporary.

Sergey Petrunia, Software Developer
Monty Program AB, http://askmonty.org
Blog: http://s.petrunia.net/blog