Re: Patch Review: Collect frequency statistics and selectivity estimation for arrays

From: Alexander Korotkov <aekorotkov(at)gmail(dot)com>
To: Nathan Boley <npboley(at)gmail(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Patch Review: Collect frequency statistics and selectivity estimation for arrays
Date: 2011-07-15 09:09:42
Message-ID: CAPpHfdvM621F_hfLUUHrA+Kf7MnzH15BjjrznnGM0u1TCr421Q@mail.gmail.com
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On Fri, Jul 15, 2011 at 2:13 AM, Nathan Boley <npboley(at)gmail(dot)com> wrote:

> First, it makes me uncomfortable that you are using the MCV and histogram
> slot
> kinds in a way that is very different from other data types.
>
> I realize that tsvector uses MCV in the same way that you do but:
>
> 1) I don't like that very much either.
> 2) TS vector is different in that equality ( in the btree sense )
> doesn't make sense, whereas it does for arrays.
>
Actually, not MCV slot is used but MCELEM. It is a different slot. ps_stats
view map both into same fileds. Surely, non-standard use of histogram slot
should be avoided.

------
With best regards,
Alexander Korotkov.

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