Re: BAcking up a Postgres Database

On Mon, Jan 15, 2001 at 07:06:41AM -0600, Tim White wrote:
> Yes, you do restore the archive logs from some backup medium. But I don't
> understand you point, the discussion relates to transaction logging, meaning
> that as dml statements are executed and committed they are logged, thus making
> it possible to re-apply them. To my knowledge Postgres does not do
> transaction logging, this makes it nearly impossible to do point of failure
> recovery without doing a pg_dump after every transaction, which is rather
> impractical.

Then perhaps it's a lack of understanding on my point.

Define "point of failure recovery."

I'm imagining something like a system crash of some sort (maybe an internal
database error and the database is corrupted somehow).

So you reinstall the latest back up.

Then you apply the transaction log.

Is that what you're saying?

Well, if the system crashed, how can you guarantee the integrity of the
transaction log in order the forward apply it?

If the database system crashed due to an internal error, and corrupted the
database files, how do you know the transaction log wasn't corrupted?

If the OS crashed, and corrupted the database, how do you know the
transaction log wasn't corrupted?

The only time I could see how you could guarantee that a transaction log
was not corrupt was if it's on a separate physical media and you had a
media issue. Wish can largely be overcome with using something like RAID
anyway.

Can you give me a scenario where you a transaction log is actually useful
and you can guarantee it is not corrupt?

mrc
--
Mike Castle Life is like a clock: You can work constantly
dalgoda(at)ix(dot)netcom(dot)com and be right all the time, or not work at all
www.netcom.com/~dalgoda/ and be right at least twice a day. -- mrc
We are all of us living in the shadow of Manhattan. -- Watchmen