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From: bruno vieira da silva <[email protected]>
To: [email protected]
Subject: Re: Query planning read a large amount of buffers for partitioned tables
Date: Wed, 15 Jan 2025 13:32:27 -0500
Message-ID: <CAB+Nuk-8MU0D=ghsjTnUL8xCKo356nvMuOu2ZjtqpBbBdS90bg@mail.gmail.com> (raw)
In-Reply-To: <CAB+Nuk9NAH8MxDK9ng9G+Vvs8XAaaV7Jc=F7FWrbF8U8WWaDEw@mail.gmail.com>
References: <CAB+Nuk9NAH8MxDK9ng9G+Vvs8XAaaV7Jc=F7FWrbF8U8WWaDEw@mail.gmail.com>

correction: Is there a way to have *visibility* on its usage?

thanks

On Wed, Jan 15, 2025 at 1:29 PM bruno vieira da silva <[email protected]>
wrote:

> Hello All.
>
> On pg 17 now we have better visibility on the I/O required during query
> planning.
> so, as part of an ongoing design work for table partitioning I was
> analyzing the performance implications of having more or less partitions.
> In one of my tests of a table with 200 partitions using explain showed a
> large amount of buffers read during planning. around 12k buffers.
>
> I observed that query planning seems to have a caching mechanism as
> subsequent similar queries require only a fraction of buffers read during
> query planning.
> However, this "caching" seems to be per session as if I end the client
> session and I reconnect the same query execution will require again to read
> 12k buffer for query planning.
>
> Does pg have any mechanism to mitigate this issue ( new sessions need to
> read a large amount of buffers for query planning) ? or should I mitigate
> this issue by the use of connection pooling.
> How is this caching done? Is there a way to have viability on its usage?
> Where is it stored?
>
> Thanks
> --
> Bruno Vieira da Silva
>


-- 
Bruno Vieira da Silva

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