Horton

Re: pg_stat_statements and "IN" conditions

Dmitry Dolgov <9erthalion6@gmail.com>

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From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Cc: Sergei Kornilov <sk@zsrv.org>, 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: 2023-02-09T15:12:26Z
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 Thu, Feb 09, 2023 at 02:30:34PM +0100, Peter Eisentraut wrote:
> On 07.02.23 21:14, Sergei Kornilov wrote:
> > 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
>
> What is the point of making this a numeric setting?  Either you want to
> merge all values or you don't want to merge any values.

At least in theory the definition of "too many constants" is different
for different use cases and I see allowing to configure it as a way of
reducing the level of surprise here. The main scenario for a numerical
setting would be to distinguish between normal usage with just a handful
of constants (and the user expecting to see them represented in pgss)
and some sort of outliers with thousands of constants in a query (e.g.
as a defence mechanism for the infrastructure working with those
metrics). But I agree that it's not clear how much value is in that.

Not having strong opinion about this I would be fine changing it to a
boolean option (with an actual limit hidden internally) if everyone
agrees it fits better.