Re: Multiple WALs for PITR ?

As an Oracle DBA primarily, moving more towards PostGreSQL as time
passes, the "alter system switch logfile" command is very often used at
the end of a hot backup to force a logfile switch and consequently
provide a full archive log set.  The command causes the database engine
to cease using the current online redo log and have it archived to the
archive log destination.  This is the only way to be sure that all
required archive logs are present in a backup to reconstitute the
database at another location.


Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA
-----Original Message-----
From: simon@2ndquadrant.com [mailto:simon@2ndquadrant.com]
Sent: Wednesday, October 06, 2004 5:36 PM
To: mkl@webde-ag.de
Cc: pgsql-admin@postgresql.org
Subject: Re: [ADMIN] Multiple WALs for PITR ?


Michael Kleiser <mkl@webde-ag.de> wrote on 06.10.2004, 16:29:08:
> I wan`t to use Point in Time Recovery
> I allread read
> http://developer.postgresql.org/docs/postgres/backup-online.html#BACKU
> P-ARCHIVING-WAL
>

Good!

> But I still wonder, if it is possible for PostgreSQL 8.0 to write
> multiple, redundant WAL-Files like Oracles with its redo-log-groups ?

Not currently.

That was something I considered, though in the end lacked both
implementation time and justification for.

If you can explain why you think that might be necessary, I'd be happy
to consider it for v8.1.

RAID-10 seems a good solution for me...

>
> Is threre an equivalent to Oracles "ALTER SYSTEM SWITCH LOGFILE" ?
>

Not currently.

Again, if you can say why we might want that, it can also be added -
other than "they have it, so we want it too" :-)

This is a likely addition for 8.1, since we will most likely want to
archive xlog files every N minutes, whatever the transaction rate,
allowing people to specify a maximum period of data loss - but this
seemed like an enhancement rather than a definite feature for 8.0

> Thanks
> Michael Kleiser
>

Glad you're interested. Your questions show you understand - good luck.

Best Regards

Simon Riggs

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