Greg Smith wrote:
On Thu, 4 Jun 2009, Geoffrey wrote:
For now, I'm still looking at the other tools as well as attempting to
verify that my current solution doesn't miss any 'little issues.'
The main thing you want to test out are that it acts sanely when the
network connection to the destination server is out, and that it doesn't
go insane if either the source or destination server run out of disk
space. You should simulate both of those things.
This has not happened as of yet, part of the test suite though.
The important thing is to validate your script cannot say you've
processed an archive file until you're absolutely positive it's stored
somewhere safe. It's really not that hard. If you've got practice
writing robust system scripts already, and it sounds like you do, I
wouldn't hesitate to use a homegrown solution here instead of
walmgr/pitrtools as long as you've done the tests I outline here.
I wrote a language parser in AWK years ago... ;) (that was ugly)
I assume a script that pulls the logs to the warm standby and then
calls pg_standby.
The way you say this makes me think you haven't really absorbed how
pg_standby works yet. You don't call it; the database recovery script
does. Your program's interaction with it is merely to drop files into
the place it expects them to be (atomically), it's a polling solution
that alternates between looking for files there/applying them to the
database/sleeping when there's no more left.
The script I mention above would be the recovery script. Since, as I
understand pg_standby, looks for files locally, then my restore script
would have to pull the files from the remote machine and drop them
somewhere where pg_standby would be looking for them. That's my thought
anyway.
If you've already gone to the trouble of writing all the pieces here
yourself, it really shouldn't be difficult to yank out the parts
pg_standby does and use it for those instead. There's a few things in
there you'll have a hard time implementing yourself that probably aren't
even on your radar yet, but are nonetheless important. Being able to
keep standby disk usage pruned easily with the restartwalfile feature
comes to mind, that one is a subtle problem that doesn't sneak up on you
until you've been in production a while.
Still studying the pg_standby code. ;)
--
Until later, Geoffrey
Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
- Benjamin Franklin
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