Chander Ganesan wrote: > Ahh...typically the term "warm standby" refers to a secondary server > that is not "hot" (i.e., queryable). I assumed that you meant you were
You are right. My fault :'( > So really, when you need to "recover", you can simply remove all the old > "wals" prior to issuing your pg_start_backup(), since they would not be > needed after your rsync. [..] > Why? If you haven't saved a backup that you made previously (using > pg_start_backup()), having archived wal files is useless. I don't see > why you just don't arbitrarily remove them immediately. Aha. Now I understand the situation. So, since pgpool-II issues online recovery in two stages, as you say, I don't really need to do WAL archiving unless there is an online recovery process getting started or happening. Therefore what I will do is modify my base-backup script to, as you suggest, activate WAL archiving. Now it all makes sense to me: 1. I do pg_start_backup 2. Therefore, from now onwards, I need to archive/store WAL files. 3. I do pg_stop_backup 4. Once the restoration is done, I don't need them anymore, so I can disable WAL archiving and delete the old, just used, already used ones. Thank you very much for your explanation, Chander, you just made everything make sense. > Note: If you are using 8.3, you can even just disable the > archive_command when you aren't doing a recovery... Yes, this is what I will do. I will look for how to do this on the online documentation (I have read that enabling/disabling WAL archiving requires restart, but enabling/disabling archive_command only needs a reload). I guess I will have to modify the /etc/postgresql/8.3/main/postgresql.conf file from the script, then ask the daemon for a reload. But I'll see if there is another way to do this that does not require altering that configuration file. > I'm not sure that I agree with your strategy in terms of preserving your > data in the case of some sort of failure, but if I understand your > problem correctly, this would serve as a pretty good solution... This database is almost read only, with scheduled updates of the contents. Therefore nightly pg_dumps are good enough (sufficient) as a backup strategy. > As a side note, I'd recommend you read up on the standard issues that > apply when using PgPool-II in multi-master replication mode with query > balancing (if you aren't already aware of them) :-) ... Yes, I believe I have. I guess you mean not being able to use CURRENT_TIMESTAMP or SERIAL in queries and stuff like that. We use the database as a data storage, all business logic remains in .NET classes or in Java classes, therefore I am pretty much sure that I won't have problems. I am still in the process of checking the code in development with the programmers so that there is no query not abiding by the rules stated in the pgpool-II readme. Thanks again for your help! It is very much appreciated. -- Jaume Sabater http://linuxsilo.net/ "Ubi sapientas ibi libertas" -- Sent via pgsql-admin mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin
