Re: lcr v5 - introduction of InvalidCommandId

On 2013-09-05 12:44:18 -0400, Robert Haas wrote:
> On Wed, Sep 4, 2013 at 12:07 PM, Andres Freund <andres@2ndquadrant.com> wrote:
> > On 2013-09-03 11:40:57 -0400, Robert Haas wrote:
> >> > 0002 wal_decoding: Introduce InvalidCommandId and declare that to be the new maximum for
CommandCounterIncrement
> >>
> >> I'm still unconvinced we want this.
> >
> > Ok, so the reason for the existance of this patch is that currently
> > there is no way to represent a "unset" CommandId. This is a problem for
> > the following patches because we need to log the cmin, cmax of catalog
> > rows and obviously there can be rows where cmax is unset.
> 
> For heap tuples, we solve this problem by using flag bits.  Why not
> adopt the same approach?

We can, while it makes the amount of data stored/logged slightly larger
and it seems to lead to less idiomatic code to me, so if there's another
-1 I'll go that way.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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