Hi, sorry for my consecutive posting. On Fri, Dec 5, 2008 at 4:00 PM, Fujii Masao <[EMAIL PROTECTED]> wrote: > Hello, > > On Fri, Dec 5, 2008 at 12:09 PM, Fujii Masao <[EMAIL PROTECTED]> wrote: >>> I was expecting you to have walreceiver and startup share an end of WAL >>> address via shared memory, so that startup never tries to read past end. >>> That way we would be able to begin reading a WAL file *before* it was >>> filled. Waiting until a file fills means we still have to have >>> archive_timeout set to ensure we switch regularly. >> >> You mean that not pg_standby but startup process waits for the next >> WAL available? If so, I agree with you in the future. That is, I just think >> that this is next TODO because there are many problems which we >> should resolve carefully to achieve it. But, if it's essential for 8.4, I >> will >> tackle it. What is your opinion? I'd like to clear up the goal for 8.4. > > Umm.. on second thought, this feature (continuous recovery without > pg_standby) seems to be essential for 8.4. So, I will try it. > > Development plan: > - Share the end of WAL address via shared memory <--- Done! > - Change ReadRecord() to wait for the next WAL *record* available. > - Change ReadRecord() to restore the WAL from archive by using > pg_standby before reaching the replication starting position, then > read the half-streaming WAL from pg_xlog. > - Add new trigger for promoting the standby to the primary. As the > trigger, when fast shudown (SIGINT) is requested during recovery, > the standby would recover the WAL up to end and become the > primary. > > What system call does walreceiver have to call against the WAL > before startup process reads it? Probably we need to call write(2), > and don't need fsync(2) in Linux. How about other platform?
I added the figures about the latest architecture into PDF file. Please check P6, 7. Is this architecture close to your imege? http://wiki.postgresql.org/wiki/NTT%27s_Development_Projects#Detailed_Design 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
