Re: PITR, checkpoint, and local relations

Vadim Mikheev <vmikheev@sectorbase.com>

From: "Mikheev, Vadim" <vmikheev@SECTORBASE.COM>
To: "'J. R. Nield'" <jrnield@usol.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Richard Tucker <richt@multera.com>, Bruce Momjian <pgman@candle.pha.pa.us>, PostgreSQL Hacker <pgsql-hackers@postgresql.org>
Date: 2002-08-02T22:00:46Z
Lists: pgsql-hackers
> > You don't need it.
> > As long as whole block is saved in log on first after
> > checkpoint (you made before backup) change to block.
> 
> I thought half the point of PITR was to be able to turn
> off pre-image logging so you can trade potential recovery

Correction - *after*-image.

> time for speed without fear of data-loss. Didn't we have
> this discussion before?

Sorry, I missed this.

So, it's already discussed what to do about partial
block updates? When system crashed just after LSN,
but not actual tuple etc, was stored in on-disk block
and on restart you compare log record' LSN with
data block' LSN, they are equal and so you *assume*
that actual data are in place too, what is not the case?

I always thought that the whole point of PITR is to be
able to restore DB fast (faster than pg_restore) *AND*
up to the last committed transaction (assuming that
log is Ok).

Vadim