Re:pg_stat_statements and "IN" conditions

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