From: Ron <ronljohnsonjr@gmail.com>
To: pgsql-admin@lists.postgresql.org
Subject: Re: need suggestion on querying big tables
Date: Tue, 6 Dec 2022 08:51:21 -0600
Message-ID: <d926084d-63a7-854b-2d8d-459d33ec7f70@gmail.com> (raw)
In-Reply-To: <CAJuN1jj6NQDUjbMH=n4zry10JMJEZ8bRi=j6uA-3_108-Tq9cQ@mail.gmail.com>
References: <CAJuN1jj6NQDUjbMH=n4zry10JMJEZ8bRi=j6uA-3_108-Tq9cQ@mail.gmail.com>
On 12/5/22 00:29, Ebin Jozer wrote:
> Hi Team,
> in postgresql 11 version we have two tables of size 435 GB and 347 GB.
> if we query on single table or if we are doing inner join on both the big
> tables, it is not displacing any output, it keeps running
>
> We can see the wait event is IO and directDatafile .
>
> Server Spec : 8 cores and 64GB RAM
> PG config : 53 GB(effective_cache), 12 GB(shared buffer)
>
> can you please suggest some ideas , how we can query on big tables and
> fasten them to get the output??
https://www.postgresql.org/docs/11/runtime-config-query.html
effective_cache_size is how much RAM *a single* query gets. "When setting
this parameter you should consider both *PostgreSQL's shared buffers*".
https://www.postgresql.org/docs/11/runtime-config-resource.html
"a reasonable starting value for *shared_buffers is 25% of the memory* in
your system. There are some workloads where even larger settings for
shared_buffers are effective, but because PostgreSQL also relies on the
operating system cache, *it is unlikely that an allocation of more than 40%
of RAM to shared_buffers will work better* than a smaller amount."
You've set effective_cache_size to 83%, when it should be at most 20%.
--
Angular momentum makes the world go 'round.
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Subject: Re: need suggestion on querying big tables
In-Reply-To: <d926084d-63a7-854b-2d8d-459d33ec7f70@gmail.com>
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