Re: speeding up planning with partitions

From: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
To: "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com>
Cc: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: speeding up planning with partitions
Date: 2018-11-15 01:24:50
Message-ID: 9a47429b-5dd7-ace4-e805-835df959355d@lab.ntt.co.jp
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On 2018/11/15 10:19, Imai, Yoshikazu wrote:
> On Tue, Nov 13, 2018 at 10:29 PM, Amit Langote wrote:
>> On 2018/11/12 13:35, Imai, Yoshikazu wrote:
>>> How amount of memory is used with above tests is...
>>>
>>> without v5 patches, Set1: 242MB
>>> without v5 patches, Set2: 247MB
>>> with v5 patches, Set1: 420MB
>>> with v5 patches, Set2: 820MB
>>
>> I understood why update/delete planning consumed more memory with the
>> patch. It was due to a problem with the patch that modifies inheritance
>> update/delete planning. The exact problem was that the query tree would
>> be translated (hence copied) *twice* for every partition! First during
>> query planning where the query tree would be translated to figure out
>> a targetlist for partitions and then again before calling
>> grouping_planner.
>> Also, the adjust_appendrel_attrs_multilevel made it worse for
>> multi-level partitioning case, because of repeated copying for root to
>> intermediate partitioned tables, as Imai-san pointed out.
>>
>> I've fixed that making sure that query tree is translated only once and
>> saved for later steps to use. Imai-san, please check the memory
>> consumption with the latest patch.
>
> Thanks for fixing!
> Now, memory consumption is lower than the previous.
>
> with v7 patches, Set1: 223MB
> with v7 patches, Set2: 226MB

Thanks for checking. So at least we no longer have any memory
over-allocation bug with the patch, but perhaps other bugs are still
lurking. :)

Regards,
Amit

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