Re: Revisiting pg_stat_statements and IN() (Was: Re: pg_stat_statements fingerprinting logic and ArrayExpr)

On Mon, Nov 30, 2015 at 02:41:02PM +0100, Shulgin, Oleksandr wrote:
> On Wed, Nov 25, 2015 at 9:13 AM, Lukas Fittl <lukas(at)fittl(dot)com> wrote:
>
> On Mon, Nov 23, 2015 at 11:53 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
>
> One specific justification he gave for not using pg_stat_statements
> was:
>
> "Doesn’t merge bind vars in IN()" (See slide #11)
>
>
> I wonder:
>
> * How do other people feel about this? Personally, I've seen enough
> problems of this kind in the field that "slippery slope" arguments
> against this don't seem very compelling.
>
>
> As someone who runs a little monitoring service thats solely based on
> pg_stat_statements data, ignoring IN list length would certainly be a good
> change.
>
> We currently do this in post-processing, together with other data cleanup
> (e.g. ignoring the length of a VALUES list in an INSERT statement).
>
> Given the fact that pgss data is normalized & you don't know which plan was
> chosen, I don't think distinguishing based on the length of the list helps
> anyone really.
>
> I see pg_stat_statements as a high-level overview of which queries have
> run, and which ones you might want to look into closer using e.g.
> auto_explain.
>
>
> I still have the plans to try to marry pg_stat_statements and auto_explain for
> the next iteration of "online query plans" extension I was proposing a few
> months ago, and the first thing I was going to look into is rectifying this
> problem with IN() jumbling.  So, have a +1 from me.

Is this a TODO?

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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