On Wed, Jun 4, 2014 at 12:50 AM, Noah Misch <n...@leadboat.com> wrote:
> As a point of procedure, I recommend separating the semijoin support into > its > own patch. Your patch is already not small; delaying non-essential parts > will > make the essential parts more accessible to reviewers. > > In the attached patch I've removed all the SEMI and ANTI join removal code and left only support for LEFT JOIN removal of sub-queries that can be proved to be unique on the join condition by looking at the GROUP BY and DISTINCT clause. Example: SELECT t1.* FROM t1 LEFT OUTER JOIN (SELECT value,COUNT(*) FROM t2 GROUP BY value) t2 ON t1.id = t2.value; Regards David Rowley
subquery_leftjoin_removal_v1.1.patch
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