I'll preemptively apologize for cross-posting this, but I follow the
lists via Google Groups, and I never saw this show up on -general
there. I see it in the archives, but the lack of discussion on -
general makes me wonder if it was widely read. Since it involves what
I perceive to be a lack of clarity in the docs, I'll offer to make up
for my cross-posting by helping to improve the docs as mentioned
below once I get things working...
I'm about to begin playing with incrementally updated backups for a
warm standby scenario, but I need some help understanding this
paragraph in postgres terms. From 23.4.5 in the 8.2.3 docs:
"If we take a backup of the standby server's files while it is
following logs shipped from the primary, we will be able to reload
that data and restart the standby's recovery process from the last
restart point. We no longer need to keep WAL files from before the
restart point. If we need to recover, it will be faster to recover
from the incrementally updated backup than from the original base
I'm specifically confused about the meaning of the following phrases:
"backup of the standby server's files" - Which files?
"reload that data" - What does this mean in postgres terms?
"last restart point" - What is this? Wouldn't it be able to restart
from the last recovered file, which would presumably occur later than
the last restart point?
Does this mean make a filesystem backup of the standby server's data
directory while it's stopped, and then start it again with that data
and the restricted set of WAL files needed to continue recovery? I'd
like to see the language here converted to words that have more
meaning in the context of postgres. I'd be happy to attempt a
revision of this section once I'm able to complete an incrementally
updated backup successfully.
Here's how I envision it playing out in practice:
1. stop standby postgres server
2. [optional] preserve data directory, remove unnecessary WAL files
3. restart standby server
Is that all there is to it?
Thomas F. O'Connell
optimizing modern web applications
: for search engines, for usability, and for performance :
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