these lines about "SPI Plan" are these PL/PGSQL functions related through SPI_prepare plan entry, right?
SPI Plan: 1024 total in 1 blocks; 600 free (0 chunks); 424 used
CachedPlan: 2048 total in 2 blocks; 304 free (1 chunks); 1744 used: xxxxxxx
CachedPlanSource: 2048 total in 2 blocks; 200 free (0 chunks); 1848 used: xxxxxxx
CachedPlanQuery: 2048 total in 2 blocks; 704 free (0 chunks); 1344 used
From: Pavel Stehule <pavel.stehule@xxxxxxxxx>
Sent: Friday, June 2, 2023 12:57 PM
To: James Pang (chaolpan) <chaolpan@xxxxxxxxx>
Cc: Laurenz Albe <laurenz.albe@xxxxxxxxxxx>; pgsql-performance@xxxxxxxxxxxxxxxxxxxx
Subject: Re: thousands of CachedPlan entry per backend
these lines about "SPI Plan" are these PL/PGSQL functions related SPI_prepare plan entry, right? Possible to set a GUC to max(cached plan) per backend ?
There is no limit for size of system cache. You can use pgbouncer that implicitly refresh session after 1 hour (and this limit can be reduced)
SPI Plan: 1024 total in 1 blocks; 600 free (0 chunks); 424 used
CachedPlan: 2048 total in 2 blocks; 304 free (1 chunks); 1744 used: xxxxxxx
CachedPlanSource: 2048 total in 2 blocks; 200 free (0 chunks); 1848 used: xxxxxxx
CachedPlanQuery: 2048 total in 2 blocks; 704 free (0 chunks); 1344 used
Thanks,
James
-----Original Message-----
From: Laurenz Albe <laurenz.albe@xxxxxxxxxxx>
Sent: Thursday, June 1, 2023 8:48 PM
To: James Pang (chaolpan) <chaolpan@xxxxxxxxx>; Pavel Stehule <pavel.stehule@xxxxxxxxx>
Cc: pgsql-performance@xxxxxxxxxxxxxxxxxxxx
Subject: Re: thousands of CachedPlan entry per backend
On Thu, 2023-06-01 at 08:50 +0000, James Pang (chaolpan) wrote:
> we found thousands of cached plan , since JDBC driver only allow max
> 256 cached prepared statements, how backend cache so many sql plans.
> If we have one function, when application call that function will make
> backend to cache every SQL statement plan in that function too? and for table triggers, have similar caching behavior ?
Yes, as long as the functions are written in PL/pgSQL.
It only affects static SQL, that is, nothing that is run with EXECUTE.
Yours,
Laurenz Albe
