[wiredfool]

I like HStore a lot better than XML for postgres. And it's Waaaaay better than the wide table model.

Way back when, I did a data model that added columns for arbitrary data fields that the users wanted in PG, and wound up with a wide table model. PG can store a surprisingly large number of fields, I think it got up to the mid to high hundreds after years of this. At the time, hstore wasn't there, xml was either not there yet, or just recently added. And the queries for EAV looked surprisingly awful, especially when added to the not exactly straightforward queries we were doing on the events.

It wound up being an extremely large, extremely sparse table, with some fields having 100% usage, most having >>.01%, and a few getting used in the 1% range. On the plus side, it was possible to index any of the fields, which was especially useful with functional or 2 column indexes.

If I had to do it again, I'd be on hstore, or maybe hstore/json. It wasn't pretty but it wasn't the fatal flaw in that startup.