Thread: Mirroring with WAL?
Hi guys, I've seen a lot of traffic around the developer lists about performing live backups by duplicating the WAL control files, but no examples of this actually working. I don't need instant fallback or any of the funky stuff listed in the TODO file, but I need to build a database which is no less than 10 minutes out of date. The source database has several gigabytes of data in it, so a pg_dump isn't really good enough :-) Has anybody managed this? -- Giles Constant, Systems Programmer Hyperlink Interactive http://www.hyperlink-interactive.co.uk
Giles Constant writes: > I've seen a lot of traffic around the developer lists about performing > live backups by duplicating the WAL control files, but no examples of this > actually working. That's because it doesn't work. There are no plans to make WAL into a replication facility, for reasons which were discussed on the developer lists as well. -- Peter Eisentraut peter_e@gmx.net http://funkturm.homeip.net/~peter
At 10:35 PM 10/17/01 +0200, Peter Eisentraut wrote:
>There are no plans to make WAL into a replication facility, for reasons
>which were discussed on the developer lists as well.
But we =are= still planning to use the WAL to implement a point-in-time
recovery process, yes?
-crl
--
Chad R. Larson (CRL22) chad@eldocomp.com
Eldorado Computing, Inc. 602-604-3100
5353 North 16th Street, Suite 400
Phoenix, Arizona 85016-3228
> At 10:35 PM 10/17/01 +0200, Peter Eisentraut wrote: > >There are no plans to make WAL into a replication facility, for reasons > >which were discussed on the developer lists as well. > > But we =are= still planning to use the WAL to implement a point-in-time > recovery process, yes? Yes, I think so. -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026
"Chad R. Larson" <chad@eldocomp.com> writes:
> At 10:35 PM 10/17/01 +0200, Peter Eisentraut wrote:
>> There are no plans to make WAL into a replication facility, for reasons
>> which were discussed on the developer lists as well.
> But we =are= still planning to use the WAL to implement a point-in-time
> recovery process, yes?
In its present form it's far too bulky to be kept around over any long
period of time --- or didn't you notice all the squawks about WAL files
overrunning disk as soon as anyone had a long-running transaction?
I'd say it's quite useless for PIT recovery unless we implement some
sort of filtering/compression process to produce an archivable WAL.
Which is doable, certainly, but it's not in the present implementation.
regards, tom lane
On Thu, 18 Oct 2001, Tom Lane wrote: > In its present form it's far too bulky to be kept around over any long > period of time --- or didn't you notice all the squawks about WAL files > overrunning disk as soon as anyone had a long-running transaction? hm.. How does this compare with the Oracle system? Are the Oracle logs smaller? This is how we perform most of our mirroring with Oracle, and yes, it does produce rather large files, but once the most recent file has been transferred over and uploaded into the mirror database, they get deleted. Admittedly this involves lots of cron writing, but it works.. :-) -- Giles Constant, Systems Programmer Hyperlink Interactive http://www.hyperlink-interactive.co.uk