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Hot Standby documentation updates

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: pgsql-docs(at)postgresql(dot)org, Simon Riggs <simon(at)2ndQuadrant(dot)com>
Subject: Hot Standby documentation updates
Date: 2010-02-18 08:11:21
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-docs
Attached is a patch that fixes up a couple of spots I felt could use 
improvement in the Hot Standby documentation.  Most of this is simple 
wordsmithing, or minor expansion of points I tried to explain more 
clearly.  A few of the edits I'd marked up on paper were already applied 
in the last update done today--even the same commas added or removed in 
some spots.  I think this section is closing in on complete and fully 
edited when we are all finding the same things to nitpick over.

The main change I added here that could use a review is this addition:

+         Waiting to acquire buffer cleanup locks.  This can occur when one
+         database backend is trying to access to data block that is 
+         by another backend that is making a change to it.  Such pins 
+         normally be very short-lived, but they can take longer than normal
+         under some circumstances, such as when a cursor executing over
+         a set of data has stopped for some reason.

That's how I interpreted what Simon told me about this subject, but I 
may not have captured the details accurately.  I didn't think that 
saying something as ominous sounding as "Waiting to acquire buffer 
cleanup locks" should be there without any description at all what 
conditions that happens under, which is what's there right now.

There are only two open things in these docs I'm still a little bugged by:

-The first paragraph mentions "restoring a backup to an exact state with 
great precision"; I have no idea what that's supposed to mean in this 

-The section about stats collection says "The stats file is deleted at 
the start of recovery, so stats from primary and standby will differ; 
this is considered a feature not a bug".  This left me going "why?", and 
some clarification of the reasoning or limitation causing that drift 
would be nice.

P.S.  I touched a few other files as well, related to a debate from 
dinner the other night that touched on Simon introducing more UK 
spelling into the docs.  This is what the docs look like now:

postgresql/doc/src/sgml $ grep -r behavior * | wc -l

postgresql/doc/src/sgml $ grep -r behaviour * | wc -l

Half of the latter were in the new material, so while on a binge fixing 
those I adjusted the mis-"behaviour"s in other sections too.

Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support

Attachment: hot-standby-doc-fix.diff
Description: text/x-patch (17.5 KB)


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