On 24 August 2015 at 07:31, Tomas Vondra <tomas.von...@2ndquadrant.com> wrote:
> > dim 100k rows, fact 1M rows > --------------------------- > > master patched > ------- ------- > .. > med 280.994 261.406 (-7%) > > > dim 1M rows, fact 10M rows > -------------------------- > > master patched > -------- -------- > .. > > med 4360.157 3648.333 (-17%) > > > dim 10M rows, fact 100M rows > ---------------------------- > > master patched > -------- -------- > .. > med 45898.408 40810.203 (-10%) > > > So the gains seem quite solid - it's not something that would make the > query an order of magnitude faster, but it's well above the noise. > > Of course, in practice the queries will be more complicated, making the > improvement less significant, but I don't think that's a reason not to > apply it. > > Many thanks for doing that performance testing. > Two minor comments on the patch: > > 1) the 'subquery' variable in specialjoin_is_unique_join is unused > > 2) in the explain output, there should probably be a space before the > '(inner unique)' text, so > > Hash Join (inner unique) ... > > instead of > > Hash Join(inner unique) > > but that's just nitpicking at this point. Otherwise the patch seems quite > solid to me. > The attached fixes these two issues. Regards David Rowley -- David Rowley http://www.2ndQuadrant.com/ <http://www.2ndquadrant.com/> PostgreSQL Development, 24x7 Support, Training & Services
unique_joins_2015-08-24.patch
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