On Fri, May 26, 2023 at 6:55 PM shveta malik <shveta.ma...@gmail.com> wrote: > > I have attempted to convert pg_get_indexdef() to use > systable_beginscan() based on transaction-snapshot rather than using > SearchSysCache(). The latter does not have any old info and thus > provides only the latest info as per the committed txns, which could > result in errors in some scenarios. One such case is mentioned atop > pg_dump.c. The patch is an attempt to fix the same pg_dump's issue. > Any feedback is welcome.
Even only in pg_get_indexdef_worker(), there are still many places where we use syscache lookup: generate_relation_name(), get_relation_name(), get_attname(), get_atttypetypmodcoll(), get_opclass_name() etc. > > There is a long list of pg_get_* functions which use SearchSysCache() > and thus may expose similar issues. I can give it a try to review the > possibility of converting all of them. Thoughts? > it would be going to be a large refactoring and potentially make the future implementations such as pg_get_tabledef() etc hard. Have you considered changes to the SearchSysCache() family so that they internally use a transaction snapshot that is registered in advance. Since we are already doing similar things for catalog lookup in logical decoding, it might be feasible. That way, the changes to pg_get_XXXdef() functions would be much easier. Regards, -- Masahiko Sawada Amazon Web Services: https://aws.amazon.com
