On Fri, Apr 21, 2023 at 12:14 AM Nikita Malakhov <huku...@gmail.com> wrote: > This limitation applies not only to wide tables - it also applies to tables > where TOASTed values > are updated very often. You would soon be out of available TOAST value ID > because in case of > high frequency updates autovacuum cleanup rate won't keep up with the > updates. It is discussed > in [1]. > > On Fri, Apr 21, 2023 at 9:39 AM Jakub Wartak <jakub.war...@enterprisedb.com> > wrote: >> I would like to ask if it wouldn't be good idea to copy the >> https://wiki.postgresql.org/wiki/TOAST#Total_table_size_limit >> discussion (out-of-line OID usage per TOAST-ed columns / potential >> limitation) to the official "Appendix K. PostgreSQL Limits" with also >> little bonus mentioning the "still searching for an unused OID in >> relation" notice. Although it is pretty obvious information for some >> and from commit 7fbcee1b2d5f1012c67942126881bd492e95077e and the >> discussion in [1], I wonder if the information shouldn't be a little >> more well known via the limitation (especially to steer people away >> from designing very wide non-partitioned tables). >> >> [1] - >> https://www.postgresql.org/message-id/flat/16722-93043fb459a41073%40postgresql.org > > [1] > https://www.postgresql.org/message-id/CAN-LCVPRvRzxeUdYdDCZ7UwZQs1NmZpqBUCd%3D%2BRdMPFTyt-bRQ%40mail.gmail.com
These 2 discussions show that it's a painful experience to run into this problem, and that the hackers have ideas on how to fix it, but those fixes haven't materialized for years. So I would say that, yes, this info belongs in the hard-limits section, because who knows how long it'll take this to be fixed. Please submit a patch. I anticipate that edits to Appendix K Postgres Limits will prompt improving the note in there about the maximum column limit, That note is too wordy, and sometimes confusing, especially for the audience that it's written for: newcomers to Postgres ecosystem. Best regards, Gurjeet https://Gurje.et http://aws.amazon.com
