Re: thousands of CachedPlan entry per backend

pá 2. 6. 2023 v 3:45 odesílatel James Pang (chaolpan) <chaolpan(at)cisco(dot)com>
napsal:

> 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)

Regards

Pavel

>
> 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(dot)albe(at)cybertec(dot)at>
> Sent: Thursday, June 1, 2023 8:48 PM
> To: James Pang (chaolpan) <chaolpan(at)cisco(dot)com>; Pavel Stehule <
> pavel(dot)stehule(at)gmail(dot)com>
> Cc: pgsql-performance(at)lists(dot)postgresql(dot)org
> 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
>