Date: Sun, 1 Feb 2015 18:37:26 -0700 (MST)
From: AlexK987 <alex.cue.987@gmail.com>
To: pgsql-performance@postgresql.org
Message-ID: <1422841046401-5836323.post@n5.nabble.com>
In-Reply-To: <6888.1422833653@sss.pgh.pa.us>
References: <1422829941197-5836319.post@n5.nabble.com>
 <6888.1422833653@sss.pgh.pa.us>
Subject: Re: Why is GIN index slowing down my query?
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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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