> > > Added to TODO:
> > >
> > > 	* Allow WAL information to recover corrupted pg_controldata
> > >...
> > > >      Using pg_control to get the checkpoint position 
> speeds up the
> > > >      recovery process, but to handle possible 
> corruption of pg_control,
> > > >      we should actually implement the reading of 
> existing log segments
> > > >      in reverse order -- newest to oldest -- in order 
> to find the last
> > > >      checkpoint. This has not been implemented, yet.
> > 
> > So if you do this, do you still need to store that information in
> > pg_control at all?

Yes: to "speeds up the recovery process".

Vadim


_____________________________________________________
Sector Data, LLC, is not affiliated with Sector, Inc., or SIAC

Tue, 18 Feb 2003 11:15:25 -0800
"Mikheev, Vadim" <VMIKHEEV@sectordata.com>
Re: WAL replay logic (was Re: [PERFORM] Mount options f
On Tue, 18 Feb 2003, Mikheev, Vadim wrote:

> > > So if you do this, do you still need to store that information in
> > > pg_control at all?
>
> Yes: to "speeds up the recovery process".

If it's going to slow down the performance of my database when not doing
recovery (because I have to write two files for every transaction,
rather than one), I couldn't care less about speeding up the recovery
process.

As far as Bruce's question goes, what kind of corruption can happen to
the log files? We write a full block at a time, I guess, so it might
make sense to checksum it to verify that the block was not partially
written.

cjs
-- 
Curt Sampson  <cjs@cynic.net>   +81 90 7737 2974   http://www.netbsd.org
    Don't you know, in this new Dark Age, we're all light.  --XTC

Wed, 19 Feb 2003 11:53:22 +0900 (JST)
Curt Sampson <cjs@cynic.net>
Re: WAL replay logic (was Re: [PERFORM] Mount options f
> > > > So if you do this, do you still need to store that information in
> > > > pg_control at all?
> >
> > Yes: to "speeds up the recovery process".
>
> If it's going to slow down the performance of my database when not doing
> recovery (because I have to write two files for every transaction,
> rather than one)

Control file is not updated "for every transaction", only on a few special
events
like checkpoint.

Vadim



Tue, 18 Feb 2003 21:31:03 -0800
"Vadim Mikheev" <vmikheev@sectordata.com>
Re: WAL replay logic (was Re: [PERFORM] Mount options f