Sorry, I didn't notice the SELECT * and I said something stupid... However my reasoning should be still valid: I mean, PG could find the few relevant rows (there's a LIMIT 30) using ONLY the index. It has all the information required inside the index! Then it can simply access to that rows on disk... It cannot take ~1 minute to access a few rows on disk (max 30 rows, actual 0 rows).
On Fri, Jan 10, 2020 at 4:18 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > Marco Colli <collimarc...@gmail.com> writes: > > As you can see it is a *index scan* and not an *index only* scan... I > don't > > understand why. The index includes all the fields used by the query... so > > an index only scan should be possible. > > Huh? The query is "select * from ...", so it retrieves *all* columns > of the table. > > regards, tom lane >
