Re: Bit datatype performance?

In article <CAPHN3JX1YNxnGsu3q5A0wGqMMwjXMcmu8LnZ72jepE2A=t23hA@mail.gmail.com>,
Antonio Vieiro <antonio@antonioshome.net> writes:

> Hi all,
> One of my entities 'E' may be 'tagged' with an arbitrary set of 256 tags 'T'.

> A first approach could be to add a M:N relationship between 'E' and 'T'.

> A second way to do this could be to add a BIT(256) datatype to 'E',
> setting bits to '1' if the entity is tagged with each one of the 256
> tags (i.e. using a 'bitmask' on the set of tags).

> Since querying entities 'E' with a certain set of tags 'T' must be
> very fast I was wondering if the second approach would be faster. What
> do you think?

I think the best way is to put the tags into a hstore column.  With a
GiST index on that column access is very fast.