Hii, Thanks for your feedback. We have decided to add a role for the extension to solve that problem. And concerning to pg_unwarm table I think we can create a new function to do that but I think a general user would not require to clear a table from buffercache. We can use bufferid and where statements to do the same if a superuser/(specific role) requests it.
Thanks. On Sat, 29 Jul 2023 at 02:55, Cary Huang <cary.hu...@highgo.ca> wrote: > > Hello > > I had a look at the patch and tested it on CI bot, it compiles and tests fine > both autoconf and meson. I noticed that the v2 patch contains the v1 patch > file as well. Not sure if intended but put there my accident. > > > I don't think "invalidating" is the right terminology. Note that we already > > have InvalidateBuffer() - but it's something we can't allow users to do, > as it > > throws away dirty buffer contents (it's used for things like dropping a > > table). > > > > How about using "discarding" for this functionality? > > I think "invalidating" is the right terminology here, it is exactly what the > feature is doing, it tries to invalidate a buffer ID by calling > InvalidateBuffer() routine inside buffer manager and calls FlushBuffer() > before invalidating if marked dirty. > > The problem here is that InvalidateBuffer() could be dangerous because it > allows a user to invalidate buffer that may have data in other tables not > owned by the current user, > > I think it all comes down to the purpose of this feature. Based on the > description in this email thread, I feel like this feature should be > categorized as a developer-only feature, to be used by PG developer to > experiment and observe some development works by invalidating one more more > specific buffers..... If this is the case, it may be helpful to add a > "DEVELOPER_OPTIONS" in GUC, which allows or disallows the > TryInvalidateBuffer() to run or to return error if user does not have this > developer option enabled. > > If the purpose of this feature is for general users, then it would make sense > to have something like pg_unwarm (exactly opposite of pg_prewarm) that takes > table name (instead of buffer ID) and drop all buffers associated with that > table name. There will be permission checks as well so a user cannot > pg_unwarm a table owned by someone else. User in this case won't be able to > invalidate a particular buffer, but he/she should not have to as a regular > user anyway. > > thanks! > > Cary Huang > ------------- > HighGo Software Inc. (Canada) > cary.hu...@highgo.ca > www.highgo.ca >
