Re: XLog: how to log?

Simon Riggs wrote:
> During recovery, we would search for a timestamp. If found exactly,
> stop. If exceeded, stop. Any transactions not committed at that point
> are, as we say, out of luck. ....This approach has a certainty about it
> that I think is much better than the error prone Xid hunting approach,
> and is also more attuned to the human reality (time matters, Xids
> don't).
> 
> Earlier, Bruce and I had discussed that for reasons of time pressure,
> the PITR code for this release would consist of 
> a) recovery to a particular Xid
> b) later, a utility that allowed xlogs to be inspected to allow DBA to
> decide which is the correct Xid to recover to.
> Those ideas don't sound as good now....
> 
> Therefore: action on me? - add a timestamp to EACH xlog record -
> something I had been shying away from.

Many transactions are going to have the same timestamp because that just
isn't precise enough to choose a particular transaction.  I agree
finding a particular xid in the logs is hard.  We could just scan the
logs to see if we find the xid before doing the recovery.

Anyway, I though we agreed to just get total recovery working for 7.5
and we can deal with recovery to a particular point later.  Or we can
just add timestamps to the wal file header and restore to a particular
wal file date timestamp.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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