Re: Using bitwise operator vs. mapping table

Brian,

> I am more familiar with the second method but I like the bits approach
> because it lets me do things like search for "any of the following event
> types" very easily and the number of types of events is limited to what
> will fit in a 32-bit integer.
>
> Any thoughts? How does that type of bitwise operation perform in
> comparison to the mapping table (where the key may be either an integer
> or a UUID)?

Actually, for this approach you want to use an INTARRAY and not a bitmap,
becuase we have special indexes (based on GIST or GIN) for INTARRAY. In
theory, one could create a GIST index for bitmaps, but nobody's done it yet.

Whether or not to use such an approach is the usual question of
denormalization. That is, using the normalized approach (an attributes child
table) will make data maintenance, validation, and future schema extensions
easier. Using the denormailzed approach (intarrays) will make specific
queries faster.

So the first question to ask before even considering denormalization is, are
your search queries, in fact, slow?

--
Josh Berkus
PostgreSQL @ Sun
San Francisco