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Re: PITR Phase 1 - Test results

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: PITR Phase 1 - Test results
Date: 2004-04-26 17:01:13
Message-ID: 1082998873.3018.6.camel@stromboli (view raw or flat)
Thread:
Lists: pgsql-hackers
Well, I guess I was fairly happy too :-)

I'd be more comfortable if I'd found more bugs though, but I'm sure the
kind folk on this list will see that wish of mine comes true!

The code is in a "needs more polishing" state - which is just the right
time for some last discussions before everything sets too solid.

Regards, Simon

On Mon, 2004-04-26 at 17:48, Bruce Momjian wrote:
> I want to come hug you --- where do you live?  !!!
> 
> :-)
> 
> ---------------------------------------------------------------------------
> 
> Simon Riggs wrote:
> > I've now completed the coding of Phase 1 of PITR. 
> > 
> > This allows a backup to be recovered and then rolled forward (all the
> > way) on transaction logs. This proves the code and the design works, but
> > also validates a lot of the earlier assumptions that were the subject of
> > much earlier debate.
> > 
> > As noted in the previous designs, PostgreSQL talks to an external
> > archiver using the XLogArchive API.
> > I've now completed:
> > - changes to PostgreSQL
> > - written a simple archiving utility, pg_arch
> > 
> > Using both of these together, I have successfully:
> > - started pg_arch
> > - started postgres
> > - taken a backup using tar
> > - ran pgbench for an extended period, so that the transaction logs taken
> > at the start have long since been recycled
> > - killed postmaster
> > - wait for completion
> > - rm -R $PGDATA
> > - restore using tar
> > - restore xlogs from archive directory
> > - start postmaster and watch it recover to end of logs
> > 
> > This has been tested through a number of times on non-trivial tests and
> > I've sat and watch the beast at work to make sure nothing wierd was
> > happening on timing.
> > 
> > At this stage:
> > Missing Functions -
> > - recovery does NOT yet stop at a specified point-in-time (that was
> > always planned for Phase 2)
> > - few more log messages required to report progress
> > - debug mode required to allow most to be turned off
> > 
> > Wrinkles
> > - code is system testable, but not as cute as it could be
> > - input from committers is now sought to complete the work
> > - you are strongly advised not to treat any of the patches as usable in
> > any real world situation YET - that bit comes next
> > 
> > Bugs
> > - two bugs currently occur during some tests:
> > 1. the notification mechanism as originally designed causes ALL backends
> > to report that a log file has closed. That works most of the time,
> > though does give rise to occaisional timing errors - nothing too
> > serious, but this inexactness could lead to later errors.
> > 2. After restore, the notification system doesn't recover fully - this
> > is a straightforward one 
> > 
> > I'm building a full patchset for this code and will upload this soon. As
> > you might expect over the time its taken me to develop this, some bitrot
> > has set in, so I'm rebuilding it against the latest dev version now, and
> > will complete fixes for the two bugs mentioned above.
> > 
> > I'm sure some will say "no words, show me the code"... I thought you all
> > would appreciate some advance warning of this, to plan time to
> > investigate and comment upon the coding.
> > 
> > Best Regards, Simon Riggs, 2ndQuadrant 
> > http://www.2ndquadrant.com
> > 
> > 
> > 
> > ---------------------------(end of broadcast)---------------------------
> > TIP 9: the planner will ignore your desire to choose an index scan if your
> >       joining column's datatypes do not match
> > 


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