Andreas Kretschmer <andreas@xxxxxxxxxxxxxxx> writes: > Am 18.04.19 um 08:52 schrieb rihad: >> Hi. Say there are 2 indexes: >> >> "foo_index" btree (foo_id) >> >> "multi_index" btree (foo_id, approved, expires_at) >> >> >> foo_id is an integer. Some queries involve all three columns in >> their WHERE clauses, some involve only foo_id. >> Would it be ok from general performance standpoint to remove >> foo_index and rely only on multi_index? I know that >> PG would have to do less work updating just one index compared to >> updating them both, but wouldn't searches >> on foo_id alone become slower? > > it depends . > > it depends on the queries you are using, on your workload. a > multi-column-index will be large than an index over just one column, > therefore you will have more disk-io when you read from such an index. I think it also depends on the average number of rows having the same foo_id.
