Horton

Re: pg_stat_statements and "IN" conditions

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Álvaro Herrera <alvherre@alvh.no-ip.org>
To: Sami Imseih <samimseih@gmail.com>
Cc: Dmitry Dolgov <9erthalion6@gmail.com>, Julien Rouhaud <rjuju123@gmail.com>, Kirill Reshke <reshkekirill@gmail.com>, Sergei Kornilov <sk@zsrv.org>, yasuo.honda@gmail.com, tgl@sss.pgh.pa.us, smithpb2250@gmail.com, vignesh21@gmail.com, michael@paquier.xyz, nathandbossart@gmail.com, stark.cfm@gmail.com, geidav.pg@gmail.com, marcos@f10.com.br, robertmhaas@gmail.com, david@pgmasters.net, pgsql-hackers@postgresql.org, pavel.trukhanov@gmail.com, Sutou Kouhei <kou@clear-code.com>
Date: 2025-03-03T11:56:24Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Introduce squashing of constant lists in query jumbling

  2. Make documentation builds reproducible

  3. Include values of A_Const nodes in query jumbling

  4. Teach planner about more monotonic window functions

  5. Split up guc.c for better build speed and ease of maintenance.

Attachments

On 2025-Feb-18, Sami Imseih wrote:

> > It's not a question about whether it's possible to implement this,
> > but about whether it makes sense. In case of plain constants it's
> > straightforward -- they will not change anything meaningfully and
> > hence could be squashed from the query. Now for a function, that
> > might return different values for the same set of constant
> > arguments, it's much less obvious and omitting such expressions
> > might have unexpected consequences.
> 
> query jumbling should not care about the behavior of the function. If
> we take a regular call to a volatile function, we will generate the
> same queryId for every call regardless of the input to the function.
> Why does the in-list case need to care about the volatility of the
> function?

I feel quite insecure about this idea TBH.  At least with immutable
functions I don't expect the system to behave wildly different than with
actual constants.  What non-immutable functions do you have in mind that
would be useful to fold as if they were constants in the IN list in such
a query?

In the meantime, here's v28 which is Dmitry's v27 plus pgindent.  No
other changes.  Dmitry, were you planning to submit a new version?

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"The problem with the future is that it keeps turning into the present"
(Hobbes)