On Tue, Mar 2, 2010 at 8:54 PM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > This still suffers from ambiguity around a shutdown checkpoint that > changes the TLI. On the page the shutdown checkpoint is on, what is the > TLI in the page header? The TLI before the checkpoint record, I presume. > Now consider a record on the same page after the checkpoint record. It's > on the new timeline, but pg_last_xlog_replay_location() will return the > old TLI, because that's on the page header.
Oh, I see. You are right. > It's not clear what it should return, a TLI corresponding the filename > of the WAL segment the record was replayed from, so that you can use > pg_xlogfile_name() to find out the filename of the WAL segment being > replayed, or the accurate TLI of the record being replayed. I'm leaning > towards the latter, it feels more correct and accurate, but you could > argue for the former too. In any case, it needs to be well-defined. I agree with you that the latter is more correct and accurate. The simple fix is updating the lastPageTLI with the CheckPoint->ThisTimeLineID when replaying the shutdown checkpoint record. Though we might need to use new variable to keep the last applied timeline instead of the lastPageTLI. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
