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help / color / mirror / Atom feedFrom: kimaidou <[email protected]>
To: Tom Lane <[email protected]>
Cc: postgres performance list <[email protected]>
Subject: Re: Bad perf when using DECLARE CURSOR on big table
Date: Tue, 18 Mar 2025 08:48:53 +0100
Message-ID: <CAMKXKO4OoEaFcfTeZZOx_icTVdUN8a5LKs=VKTpVqQ-jv27Qww@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CAMKXKO6_evfQp80xx5tFkoziHW+62mHg=YKenUEb5VTdnXT=Sg@mail.gmail.com>
<[email protected]>
Indeed, increasing cursor_tuple_fraction TO 0.2 did the trick.
Thanks for the hint Tom !
Le lun. 17 mars 2025 à 16:22, Tom Lane <[email protected]> a écrit :
> kimaidou <[email protected]> writes:
> > I have seen that this DECLARE has bad perf compared to a simple SQL
> query :
>
> > Simple SQL query
> > =====
> > https://explain.dalibo.com/plan/042bc4dc2449adfe
> > 96ms
>
> > DECLARE CURSOR for the same query
> > =====
> > https://explain.dalibo.com/plan/bh83fc0db500a79g#
> > 171 031 ms !!
>
> Raising cursor_tuple_fraction would probably help this case.
>
> regards, tom lane
>
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Subject: Re: Bad perf when using DECLARE CURSOR on big table
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