RE: Questions about btree_gin vs btree_gist for low cardinality columns

> In the case of a single column with a small set of distinct values over a large set of rows, how would a Bloom filter be preferable to, say, a GIN index on an integer value? 

I don't think it would - it's probably better suited to the multi-column case you described previously.

> I have to say, this is actually a good reminder in my case. We've got a lot of small-distinct-values-big-rows columns. For example, "server_id", "company_id", "facility_id", and so on. Only a handful of parent keys with many millions of related rows. Perhaps it would be conceivable to use a Bloom index to do quick lookups on combinations of such values within the same table. I haven't tried Bloom indexes in Postgres, this might be worth some experimenting.

Yes, this is more like the use case I was thinking of.

Steve.