> Attached is the updated version of the patch. I refactored the code, fixed > some bugs, added lots of source code comments, improved the document, > but didn't change the basic design. Please check this patch, and let's use > this patch as the base if you agree with that.
Thanks for update patch. Yes. I agree. > In the current patch, there is no safeguard for preventing users from > taking backup during recovery when FPW is disabled. This is unsafe. > Are you planning to implement such a safeguard? Yes. I want to reference the following Fujii's comments. ------------------------------------------------------------------------- > Right. Let me explain again what I'm thinking. > > When FPW is changed, the master always writes the WAL record > which contains the current value of FPW. This means that the standby > can track all changes of FPW by reading WAL records. > > The standby has two flags: One indicates whether FPW has always > been TRUE since last restartpoint. Another indicates whether FPW > has always been TRUE since last pg_start_backup(). The standby > can maintain those flags by reading WAL records streamed from > the master. > > If the former flag indicates FALSE (i.e., the WAL records which > the standby has replayed since last restartpoint might not contain > required FPW), pg_start_backup() fails. If the latter flag indicates > FALSE (i.e., the WAL records which the standby has replayed > during the backup might not contain required FPW), > pg_stop_backup() fails. > > If I'm not missing something, this approach can address the problem > which you're concerned about. ------------------------------------------------------------------------- Regards. -------------------------------------------- Jun Ishizuka NTT Software Corporation TEL:045-317-7018 E-Mail: ishizuka....@po.ntts.co.jp -------------------------------------------- -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers