Hi,
On 2023-07-08 08:48:00 -0400, Andrew Dunstan wrote:
> On 2023-07-02 Su 22:15, Andrew Dunstan wrote:
> > > > > Separately, will this work correctly with procedures keeping values alive
> > > > > across transactions?
> > > > That might be an issue. But couldn't we make this cache just live for
> > > > the life of the process? It's unlikely to get large.
> > > I don't have a good handle about how big it'd end up being in some of the less
> > > common workloads. I can imagine workloads with temp tables or such churning
> > > through a lot of default values - often the "keyed by value" approach will
> > > save the day, but I imagine not always.
> >
> > The maximum number of entries in the table is the number of pg_attribute
> > rows with atthasmissing = true and attbyval = false. In practice I
> > suspect that's mostly going to be fairly low.
It's not really bound by that, because the set of rows can change over
time. Particularly with temp tables.
> The thread seems to have died down a bit. Do we have a consensus on Tom's
> approach?
I guess so. It's far from pretty, but nobody really has come up with something
better.
Greetings,
Andres Freund