Re: Columns correlation and adaptive query optimization

From: Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
To: Yugo NAGATA <nagata(at)sraoss(dot)co(dot)jp>, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
Cc: Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>, David Steele <david(at)pgmasters(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Columns correlation and adaptive query optimization
Date: 2021-03-19 16:58:27
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On 19.03.2021 12:17, Yugo NAGATA wrote:
> On Wed, 10 Mar 2021 03:00:25 +0100
> Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
>> What is being proposed here - an extension suggesting which statistics
>> to create (and possibly creating them automatically) is certainly
>> useful, but I'm not sure I'd call it "adaptive query optimization". I
>> think "adaptive" means the extension directly modifies the estimates
>> based on past executions. So I propose calling it maybe "statistics
>> advisor" or something like that.
> I am also agree with the idea to implement this feature as a new
> extension for statistics advisor.
>> BTW Why is "qual" in
>> static void
>> AddMultiColumnStatisticsForQual(void* qual, ExplainState *es)
>> declared as "void *"? Shouldn't that be "List *"?
> When I tested this extension using TPC-H queries, it raised segmentation
> fault in this function. I think the cause would be around this argument.
> Regards,
> Yugo Nagata
Attached please find new version of the patch with
AddMultiColumnStatisticsForQual parameter type fix and one more fix
related with handling synthetic attributes.
I can not reproduce the crash on TPC-H queries, so if the problem
persists, can you please send me stack trace and may be some other
information helping to understand the reason of SIGSEGV?

Thanks in advance,

Attachment Content-Type Size
auto_explain_create_statistic-9.patch text/x-patch 14.1 KB

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