Hi, Thanks for the comment!
On Tue, Jul 7, 2009 at 12:16 AM, Tom Lane<t...@sss.pgh.pa.us> wrote: > Fujii Masao <masao.fu...@gmail.com> writes: >> In order for the primary server (ie. a normal backend) to read an archived >> file, >> restore_command needs to be specified in also postgresql.conf. In this case, >> how should we handle restore_command in recovery.conf? > > I confess to not having paid much attention to this thread so far, but ... > what is the rationale for having such a capability at all? If the XLOG files which are required for recovery exist only in the primary server, the standby server has to read them in some way. For example, when the latest XLOG file of the primary server is 09 and the standby server has only 01, the missing files (02-08) has to be read for recovery by the standby server. In this case, the XLOG records in 09 or later are shipped to the standby server in real time by synchronous replication feature. The problem which I'd like to solve is how to make the standby server read the XLOG files (XLOG file, backup history file and timeline history) which exist only in the primary server. In the previous patch, we had to manually copy those missing files to the archive of the standby server or use the warm-standby mechanism. This would decrease the usability of synchronous replication. So, I proposed one of the solutions which makes the standby server read those missing files automatically: introducing new function pg_read_xlogfile() which reads the specified XLOG file. Is this solution in the right direction? Do you have another reasonable solution? > It seems to > me to be exposing implementation details that we do not need to expose, > as well as making assumptions that we shouldn't make (like there is > exactly one archive and the primary server has read access to it). You mean that one archive is shared between two servers? If so, no. I attached the picture of the environment which I assume. Please feel free to comment. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
pg_read_xlogfile.pdf
Description: Adobe PDF document
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