Antonin Houska <a...@cybertec.at> wrote: > Andres Freund <and...@anarazel.de> wrote: > > But I'm not sure it's quite the right idea. I'm not sure I fully > > understand the design of 0dc8ead46, but it looks to me like it's > > intended to allow users of the interface to have different ways of > > opening files. If we just close() the fd that'd be a bit more limited. > > It should have allowed users to have different ways to *locate the segment* > file. The WALSegmentOpen callback could actually return file path instead of > the file descriptor and let WALRead() perform the opening/closing, but then > the WALRead function would need to be aware whether it is executing in backend > or in frontend (so it can use the correct function to open/close the file).
Well, #ifdef FRONTEND can be used to distinguish the caller of WALRead(). However now that I tried to adjust the API, I see that pg_waldump.c:WALDumpOpenSegment uses specific logic to open the file. So if the callback only returned the file name, there would be no suitable place for the things that WALDumpOpenSegment does. -- Antonin Houska Web: https://www.cybertec-postgresql.com
