Re: [HACKERS] Runtime Partition Pruning

From: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Amit Langote <amitlangote09(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, amul sul <sulamul(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>
Subject: Re: [HACKERS] Runtime Partition Pruning
Date: 2018-04-12 22:01:52
Message-ID: CAKJS1f836D=r5w6VgPOdiueYvjTnuUdqpcbfWyAYw5+CUVTXfA@mail.gmail.com
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On 13 April 2018 at 04:57, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> BTW, looking at ExecSetupPartitionPruneState:
>
> /*
> * Create a sub memory context which we'll use when making calls to the
> * query planner's function to determine which partitions will
> match. The
> * planner is not too careful about freeing memory, so we'll ensure we
> * call the function in this context to avoid any memory leaking in the
> * executor's memory context.
> */
>
> This is a sloppy cut-and-paste job, not only because somebody changed
> one copy of the word "planner" to "executor" and left the others
> untouched, but also because the rationale isn't really correct for the
> executor anyway, which has memory contexts all over the place and
> frees them all the time. I don't know whether the context is not
> needed at all or whether the context is needed but the rationale is
> different, but I don't buy that explanation.

The comment is written exactly as intended. Unsure which of the
"planner"s you think should be "executor".

The context is needed. I can easily produce an OOM without it.

--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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