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.kla...@aklaver.com <mailto:adrian.kla...@aklaver.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.kla...@aklaver.com <mailto:adrian.kla...@aklaver.com>


--
Adrian Klaver
adrian.kla...@aklaver.com



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