Re: XLog: how to log?

Tom Lane wrote:
> Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> writes:
> > Hmm ... I think it should be forbidden to quote a subtrans Xid as
> > rollforward point. Not sure if that can be done though, or how to do
> > it.
>
> Seems like a nonissue, unless the XLOG trace makes a subtrans look the
> same as a main trans, which it'd not do would it?
>
> We could allow specification of a subtrans ID to be interpreted the same
> as specification of its parent main trans. Dunno if that's actually
> useful to anyone. Actually, I'd think that people would generally
> specify recovery up to a particular timestamp, and not be interested in
> xact numbers at all ...

I don't think timestamp is going to be precise enough. Basically I can
see someone saying I want recovery up to 4am, but anything more specific
will need xid. I suggested that we write an xlog dump tool so you can
see the xids (with some xid details) and rough timestamps stored in the
WAL file and choose the xid for recovery.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073