From: | Torge <torgato(at)posteo(dot)de> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: Feature request for count_estimate(samplesize) aggregate or SAMPLE keyword |
Date: | 2022-09-01 01:49:40 |
Message-ID: | f0bcde70-0257-7b08-4e51-57e114314925@posteo.de |
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Lists: | pgsql-general |
I am not aware of this, sounds like what I want. Will look into it. Thanks!
Am 01.09.22 um 03:47 schrieb Tom Lane:
> Torge <torgato(at)posteo(dot)de> writes:
>> Now I would like to humbly propose a feature that gives an easy way to
>> get a quick count estimate for any condition - index based or not -
>> based on a random sample of rows, that does not require a custom
>> function creation or complex SQL statement
> Can't you do that already using TABLESAMPLE? For example, to
> use a 1% sample:
>
> select count(*) * 100 from mytab tablesample system(1) where <condition>;
>
> You do have to remember to multiply by the factor corresponding
> to your sample rate, but aside from that annoyance this (a)
> already exists, (b) is SQL-standard, and (c) can be adapted to
> a lot of other kinds of analysis besides plain count(*).
>
> regards, tom lane
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