Re: Why is GIN index slowing down my query? - Mailing list pgsql-performance

From AlexK987
Subject Re: Why is GIN index slowing down my query?
Date
Msg-id 1422841046401-5836323.post@n5.nabble.com
Whole thread Raw
In response to Re: Why is GIN index slowing down my query?  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Why is GIN index slowing down my query?
List pgsql-performance
Tom,

This is a realistic case: everyone have Python and Java skills, but PostGis
and Haskell and Closure are rare. If we are looking for a person that has
all the skills required for a task (array[1, 15]), that is "skills <@
array[1, 15] " and not the opposite, right?

Also can you explain why " entries for "0" and "1" swamp everything else so
that the planner
doesn't know that eg "15" is really rare. " I thought that if a value is not
found in the histogram, than clearly that value is rare, correct? What am I
missing here?

I hear what you are saying about "don't keep both extremely common and
extremely rare entries in the same array", but I cannot predict the future,
so I do not know which values are going to be common next year, or two years
later. So I think it would be very difficult to follow this advice.

What do you think?



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