Horton

Re: pg_stat_statements and "IN" conditions

Dmitry Dolgov <9erthalion6@gmail.com>

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From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Sergei Kornilov <sk@zsrv.org>
Cc: Michael Paquier <michael@paquier.xyz>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Marcos Pegoraro <marcos@f10.com.br>, vignesh C <vignesh21@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Zhihong Yu <zyu@yugabyte.com>, David Steele <david@pgmasters.net>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Greg Stark <stark@mit.edu>, Pavel Trukhanov <pavel.trukhanov@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2023-02-09T15:02:38Z
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.

> On Tue, Feb 07, 2023 at 11:14:52PM +0300, Sergei Kornilov wrote:
> Hello!

Thanks for reviewing.

> Unfortunately, rebase is needed again due to recent changes in queryjumblefuncs ( 9ba37b2cb6a174b37fc51d0649ef73e56eae27fc )

Yep, my favourite game, rebaseball. Will post a new version soon, after
figuring out all the recent questions.

> It seems a little strange to me that with const_merge_threshold = 1, such a test case gives the same result as with const_merge_threshold = 2
>
> select pg_stat_statements_reset();
> set const_merge_threshold to 1;
> select * from test where i in (1,2,3);
> select * from test where i in (1,2);
> select * from test where i in (1);
> select query, calls from pg_stat_statements order by query;
>
>                 query                | calls
> -------------------------------------+-------
>  select * from test where i in (...) |     2
>  select * from test where i in ($1)  |     1
>
> Probably const_merge_threshold = 1 should produce only "i in (...)"?

Well, it's not intentional, probably I need to be more careful with
off-by-one. Although I agree to a certain extent with Peter questioning
the value of having numerical option here, let me think about this.

> const_merge_threshold is "the minimal length of an array" (more or equal) or "array .. length is larger than" (not equals)? I think the documentation is ambiguous in this regard.
>
> I also noticed a typo in guc_tables.c: "Sets the minimal numer of constants in an array" -> number

Yep, I'll rephrase the documentation.