Re: Broken resetting of subplan hash tables

From: Ranier Vilela <ranier(dot)vf(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Andreas Karlsson <andreas(at)proxel(dot)se>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Justin Pryzby <pryzby(at)telsasoft(dot)com>
Subject: Re: Broken resetting of subplan hash tables
Date: 2020-03-01 12:52:47
Message-ID: CAEudQAppnvESFqR4tq6rJZcteLw4k3aYLzmzW5E_gtMhN1cYZg@mail.gmail.com
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Em sáb., 29 de fev. de 2020 às 18:44, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> escreveu:

> "throw it away" sure looks like it means the entire hashtable, not just
> its tuple contents.
>
I don't know if I can comment clearly to help, but from my experience,
destroying and rebuilding the hashtable is a waste if possible, resetting
it.
By analogy, I have code with arrays where, I reuse them, with only one
line, instead of reconstructing them.
a->nelts = 0; / * reset array * /
If possible, doing the same for hashtables would be great.

regards,
Ranier Vilela

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