Re: Can we get rid of repeated queries from pg_dump?

Greetings,

* Tom Lane (tgl(at)sss(dot)pgh(dot)pa(dot)us) wrote:
> Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> writes:
> > Another pointlessly repetitive query is in getTriggers, which we run
> > once per table to be dumped containing triggers. We could reduce that
> > by running it in bulk for many relations at a time. I suppose it's
> > normally not hurtful, but as we grow the number of partitions we allow
> > it's going to become a problem.
>
> Perhaps. In the regression database, only ~10% of the tables have
> triggers, so it's likely not going to yield any measurable gain there.
> But databases that make heavier use of foreign keys might see a win.

It sure seems like in just about all cases fewer queries is going to be
better.

> Another thing I've wondered about before is whether it could make sense
> to read pg_attribute once rather than once per table. There might be
> a fair amount of wasted work if the dump is selective, and in big DBs
> the sheer size of that result could be a problem. But those reads are
> definitely way up there on the number-of-queries scale.

Yeah, I've thought about this before too. Would sure be nice if there
was a way that we could query the catalog selectively based on the
options the user has passed in but do so in as few queries as possible.

Thanks,

Stephen