Re: Increased storage size of jsonb in pg15

On 12/28/23 12:41, Sean Flaherty wrote:
> I'm rather new to the mailing list, are there any additional steps I
> should take (i.e. posting to pgsql-hackers, etc.)?
>

For what purpose? You are seeing differences in compression strategies
between lz4 and pglz. The 'fix' would be to go back to pglz.

>
> On Thu, Dec 28, 2023 at 11:23 AM Adrian Klaver
> <adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>> wrote:
>
> On 12/28/23 09:13, Sean Flaherty wrote:
> > Follow-up:
> > Working with AWS, we found that starting in RDS Postgres 15, the
> > default_toast_compression parameter is set to use lz4 compression
> > instead of pglz.  This resulted in the increased json storage
> size we
> > were seeing.
> >
> > I have been able to reproduce the increased storage size on RDS
> Postgres
> > and using my local docker instance of postgres 15.5 by changing the
> > local default_toast_compression value in postgresql.conf.
> >
> > I have attached the test script we use to create a table, insert
> some
> > test records and a query to test the JSON data size on disk.
>
> I can confirm I see the same results using Postgres 16 installed from
> the PGDG repo on Ubuntu 22.04. That the lz4 data size is greater then
> the pglz data size.
>
> >
> >
> > Kind regards,
> > Sean
> >
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com