Re: Statistics Import and Export

>
>
> > BEGIN;
> > LOCK TABLE schema.relation IN SHARE UPDATE EXCLUSIVE MODE;
> > LOCK TABLE pg_catalog.pg_statistic IN ROW UPDATE EXCLUSIVE MODE;
> > SELECT pg_import_rel_stats('schema.relation', ntuples, npages);
> > SELECT pg_import_pg_statistic('schema.relation', 'id', ...);
> > SELECT pg_import_pg_statistic('schema.relation', 'name', ...);
>
> How well would this simplify to the following:
>
> SELECT pg_import_statistic('schema.relation', attname, ...)
> FROM (VALUES ('id', ...), ...) AS relation_stats (attname, ...);
>
> Or even just one VALUES for the whole statistics loading?
>

I'm sorry, I don't quite understand what you're suggesting here. I'm about
to post the new functions, so perhaps you can rephrase this in the context
of those functions.

> I suspect the main issue with combining this into one statement
> (transaction) is that failure to load one column's statistics implies
> you'll have to redo all the other statistics (or fail to load the
> statistics at all), which may be problematic at the scale of thousands
> of relations with tens of columns each.

Yes, that is is a concern, and I can see value to having it both ways (one
failure fails the whole table's worth of set_something() functions, but I
can also see emitting a warning instead of error and returning false. I'm
eager to get feedback on which the community would prefer, or perhaps even
make it a parameter.