RE: [HACKERS] Cached plans and statement generalization

> -----Original Message-----
> From: Konstantin Knizhnik [mailto:k.knizhnik@postgrespro.ru]
> Sent: Wednesday, August 1, 2018 4:53 PM
> To: Yamaji, Ryo/山地 亮 <yamaji.ryo@jp.fujitsu.com>
> Cc: PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
> Subject: Re: [HACKERS] Cached plans and statement generalization
> 
> I failed to reproduce the problem.
> I used the following non-default configuration parameters:
> 
> autoprepare_limit=1
> autoprepare_threshold=1
> 
> create dummy database:
> 
> create table foo(x integer primary key, y integer); insert into foo values
> (generate_series(1,10000), 0);
> 
> and run different queries,  like:
> 
> postgres=# select *  from foo where x=1; postgres=# select *  from foo
> where x+x=1; postgres=# select *  from foo where x+x+x=1; postgres=#
> select *  from foo where x+x+x+x=1; ...
> 
> and check size of CacheMemoryContext using gdb - it is not increased.
> 
> Can you please send me your test?


I checked not CacheMemoryContext but "plan cache context". 
Because I think that the memory context that autoprepare mainly uses is "plan cache context". 

Non-default configuration parameter was used as well as Konstantin. 
autoprepare_limit=1
autoprepare_threshold=1

The procedure of the test that I did is shown below. 

create dummy database
create table test (key1 integer, key2 integer, ... , key100 integer);
insert into test values (1, 2, ... , 100);

And, different queries are executed. 
select key1 from test where key1=1 and key2=2 and ... and key100=100;
select key2 from test where key1=1 and key2=2 and ... and key100=100;
select key3 from test where key1=1 and key2=2 and ... and key100=100;...

And, "plan cache context" was confirmed by using gdb.