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Subject: Re: effective_cache_size cfg
From: Scott Ribe <scott_ribe@elevated-dev.com>
In-Reply-To: <1539626643680.56712@nrc-cnrc.gc.ca>
Date: Mon, 15 Oct 2018 14:03:11 -0600
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To: "Ghiurea, Isabella" <Isabella.Ghiurea@nrc-cnrc.gc.ca>
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>=20
> On Oct 15, 2018, at 12:04 PM, Ghiurea, Isabella =
<Isabella.Ghiurea@nrc-cnrc.gc.ca> wrote:
>=20
> I am running PGSQL 10.4  on Cent OS  Pg instance has ' =
effective_cache_size' parameter not  enabled I would like to learn what =
will  the optimizer behavior be in this case ?
>  ( default is set to 4GB , I was  thinking  PG 's optimizer will try =
to use all available OS RAM when trying to estimate a query, is this the =
case)

That's merely a hint to the optimizer as to how much file data is likely =
to be cached by the OS--it doesn't directly affect any PG allocations, =
rather it might influence PG's choice of steps to carry out a query, =
which of course could indirectly change the RAM that PG would use.

--
Scott Ribe
scott_ribe@elevated-dev.com
https://www.linkedin.com/in/scottribe/