> > Could you not rewrite this as a simple join though? > > Hmmm, I don't see how. Then again, I'm pretty much the village > idiot w.r.t. SQL... > > The inner select is locating a set of (2049) ids (actually from > the same table, since 'attributes' is just a view into > 'attributes_table'). The outer select is then locating all > records (~30-40K) that have any of those ids. Is that really > something a JOIN could be used for?
This may be a question for SQL theoretists, but I don't think I've ever run across a query with a 'where in' clause that couldn't be written as a join. I think linguistically 'where in' may even be a special case of 'join'. Yet another question for the theoretists: Would it be possible to optimize a 'where in' query by rewriting it as a join? -- Mike Nolan ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
