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help / color / mirror / Atom feedFrom: Dmitry Dolgov <[email protected]>
To: Tom Lane <[email protected]>
Cc: Zhihong Yu <[email protected]>
Cc: David Steele <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Cc: Greg Stark <[email protected]>
Cc: Pavel Trukhanov <[email protected]>
Subject: Re: pg_stat_statements and "IN" conditions
Date: Thu, 10 Mar 2022 17:38:37 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <CALNJ-vRRrdXu9igzh5PFTBghK5hnQWF6gpntTPo_+Agq_TsT5Q@mail.gmail.com>
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<20210318155002.ggrgf2p2mvaodcox@localhost>
<20210615151850.6nsue7z5xjhpytle@localhost>
<20210616140212.kt3n5wi3alfz5i5d@localhost>
<20210930134930.d4vzwhvxhfpk2zxt@localhost>
<CALNJ-vSJvaJbcXr46JMyWFT5rO3BdaHO2E=xnAbLNDw1cyUJ-A@mail.gmail.com>
<20210930150957.tz3h3unjyrzatw6e@localhost>
<[email protected]>
<[email protected]>
> On Wed, Jan 05, 2022 at 10:11:11PM +0100, Dmitry Dolgov wrote:
> > On Tue, Jan 04, 2022 at 06:02:43PM -0500, Tom Lane wrote:
> > We can debate whether the rules proposed here are good for
> > pg_stat_statements or not, but it seems inevitable that they will be a
> > disaster for some other consumers of the query hash.
>
> Hm, which consumers do you mean here, potential extension? Isn't the
> ability to use an external module to compute queryid make this situation
> possible anyway?
>
> > do you really think that a query with two int
> > parameters is equivalent to one with five float parameters for all
> > query-identifying purposes?
>
> Nope, and it will be hard to figure this out no matter which approach
> we're talking about, because it mostly depends on the context and type
> of queries I guess. Instead, such functionality should allow some
> reasonable configuration. To be clear, the use case I have in mind here
> is not four or five, but rather a couple of hundreds constants where
> chances that the whole construction was generated automatically by ORM
> is higher than normal.
>
> > I can see the merits of allowing different numbers of IN elements
> > to be considered equivalent for pg_stat_statements, but this patch
> > seems to go far beyond that basic idea, and I fear the side-effects
> > will be very bad.
>
> Not sure why it goes far beyond, but then there were two approaches
> under consideration, as I've stated in the first message. I already
> don't remember all the details, but another one was evolving around
> doing similar things in a more limited fashion in transformAExprIn. The
> problem would be then to carry the information, necessary to represent
> the act of "merging" some number of queryids together. Any thoughts
> here?
>
> The idea of keeping the original queryid untouched and add another type
> of id instead sounds interesting, but it will add too much overhead for
> a quite small use case I guess.
```
Thu, 10 Mar 2022
New status: Waiting on Author
```
This seems incorrect, as the only feedback I've got was "this is a bad
idea", and no reaction on follow-up questions.
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Subject: Re: pg_stat_statements and "IN" conditions
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