On Sun, Oct 24, 2021 at 2:15 AM Bossart, Nathan <bossa...@amazon.com> wrote: > Here is an attempt at doing this. Archive modules are expected to > declare _PG_archive_module_init(), which can define GUCs, register > background workers, etc. This function must at least define the > archive callbacks. For now, I've introduced two callbacks. The first > is for checking that the archive module is configured, and the second > contains the actual archiving logic.
I don't see why this patch should need to make any changes to internal_load_library(), PostmasterMain(), SubPostmasterMain(), or any other central point of control, and I don't think it should. pgarch_archiveXlog() can just load the library at the time it's needed. That way it only gets loaded in the archiver process, and the required changes are much more localized. Like instead of asserting that the functions are initialized, just load_external_function(libname, "_PG_archive_module_init") and call it if they aren't. I think the attempt in check_archive_command()/check_archive_library() to force exactly one of those two to be set is not going to work well and should be removed. In general, GUCs whose legal values depend on the values of other GUCs don't end up working out well. I think what should happen instead is that if archive_library=shell then archive_command does whatever it does; otherwise archive_command is without effect. -- Robert Haas EDB: http://www.enterprisedb.com
