| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Vik Fearing <vik(at)postgresfriends(dot)org> |
| Cc: | Aleksander Alekseev <aleksander(at)timescale(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Andrei Lepikhov <lepihov(at)gmail(dot)com>, wenhui qiu <qiuwenhuifx(at)gmail(dot)com> |
| Subject: | Re: Should we optimize the `ORDER BY random() LIMIT x` case? |
| Date: | 2025-05-16 21:21:08 |
| Message-ID: | 99515.1747430468@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Vik Fearing <vik(at)postgresfriends(dot)org> writes:
> On 16/05/2025 15:01, Tom Lane wrote:
>> Seems to me the obvious answer is to extend TABLESAMPLE (or at least, some
>> of the tablesample methods) to allow it to work on a subquery.
> Isn't this a job for <fetch first clause>?
> FETCH SAMPLE FIRST 10 ROWS ONLY
How is that an improvement on TABLESAMPLE? Or did the committee
forget that they already have that feature?
TABLESAMPLE seems strictly better to me here because it affords
the opportunity to specify one of several methods, which seems
like it would be useful in this context.
regards, tom lane
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