Should team be a taxonomy? If so, am I essentially setting up a
duplicate taxonomy for each post type (one for articles and one for
events and one for people)?
You can assign the same taxonomy to multiple post types, so I don’t see why you’d need to duplicate it.
I will definitely be querying based on the team value for all 3 post
types, so I’m assuming meta data isn’t ideal since the meta value is
not indexed in the database. Is it a bad idea to add an index for the
meta value column in that DB table?
Indexes tend to be left alone when the Core updates. I am speaking from experience so that is not official and there is no guarantee that that will be the case.
I don’t think I understand your goal well enough to say which is best (though I probably lean toward “taxonomy”), however…
- Taxonomy queries are complicated as there are three tables involved
just for the taxonomy, and then the post tables themselves, though
they are not necessarily used for all queries. - Meta queries are comparably much much simpler. Even without the
indexes you need, it may be quicker.
My answer would be, if you really are going to have data and traffic worth worrying about the performance difference, set each up on dev stack and profile it.