At Fri, 11 Mar 2022 15:39:13 -0500, Robert Haas <robertmh...@gmail.com> wrote in > On Thu, Mar 10, 2022 at 9:38 PM Kyotaro Horiguchi > <horikyota....@gmail.com> wrote: > > It seems to me too rigorous that pg_get_wal_records_info/stats() > > reject future LSNs as end-LSN and I think WARNING or INFO and stop at > > the real end-of-WAL is more kind to users. I think the same with the > > restriction that start and end LSN are required to be different. > > In his review just yesterday, Jeff suggested this: "Don't issue > WARNINGs or other messages for ordinary situations, like when > pg_get_wal_records_info() hits the end of WAL." I think he's entirely > right, and I don't think any patch that does otherwise should get
It depends on what we think is the "ordinary" here. If we don't expect that specified LSN range is not filled-out, the case above is ordinary and no need for any WARNING nor INFO. I'm fine with that definition here. > committed. It is worth remembering that the results of queries are > often examined by something other than a human being sitting at a psql > terminal. Any tool that uses this is going to want to understand what > happened from the result set, not by parsing strings that may show up > inside warning messages. Right. I don't think it is right that WARNING is required to evaluate the result. And I think that the WARNING like 'reached end-of-wal before end LSN' is a kind that is not required in evaluation of the result. Since each WAL row contains at least start LSN. > I think that the right answer here is to have a function that returns > one row per record parsed, and each row should also include the start > and end LSN of the record. If for some reason the WAL records return > start after the specified start LSN (e.g. because we skip over a page > header) or end before the specified end LSN (e.g. because we reach > end-of-WAL) the user can figure it out from looking at the LSNs in the > output rows and comparing them to the LSNs provided as input. I agree with you here. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
