From: Sergei Kornilov <sk@zsrv.org>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: Michael Paquier <michael@paquier.xyz>,
	Alvaro Herrera <alvherre@alvh.no-ip.org>,
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	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>
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Subject: Re:pg_stat_statements and "IN" conditions
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Date: Tue, 07 Feb 2023 23:14:52 +0300
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Hello!

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

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 (...)"?

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

regards, Sergei