Re: [HACKERS] REPLICA IDENTITY FULL

Andres Freund wrote:
> On 2017-06-23 13:05:21 -0400, Alvaro Herrera wrote:
> > Tom Lane wrote:
> > > Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes:
> > > > Any thoughts about keeping datumAsEqual() as a first check?  I did some
> > > > light performance tests, but it was inconclusive.
> > > 
> > > Seems like it would tend to be a win if, in fact, the values are
> > > usually equal.  If they're usually not, then it's a loser.  Do
> > > we have any feeling for which case is more common?
> 
> Seems like a premature optimization to me - if you care about
> performance and do this frequently, you're not going to end up using
> FULL.  If we want to performance optimize, it'd probably better to
> lookup candidate keys and use those if available.

I can get behind that argument.

> > who in their right minds would use floating point columns as part of
> > replica identity ...?
> 
> Since this is FULL, it'll be all columns...

Yeah, I was thinking you shouldn't have floating point columns if you're
going to use FULL as identity.  But you're tautologically right: doing
the wrong thing is likely not the right thing to do.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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