From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Proposal: collect frequency statistics for arrays |
Date: | 2011-02-18 18:57:55 |
Message-ID: | 12406.1298055475@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Alexander Korotkov <aekorotkov(at)gmail(dot)com> writes:
> I have following proposal. Currently the ts_typanalyze function accumulates
> frequency statistics for ts_vector using lossy counting technique. But no
> frequency statistics is collecting over arrays. I'm going to generalize
> ts_typanalyze to make it collecting statistics for arrays too. ts_typanalyze
> internally uses lexeme comparison and hashing. I'm going to use functions
> from default btree and hash opclasses of array element type in this
> capacity. Collected frequency statistics for arrays can be used for && and
> @> operators selectivity estimation.
It'd be better to just make a separate function for arrays, instead of
trying to kluge ts_typanalyze to the point where it'd cover both cases.
regards, tom lane
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