1) Postgres optimizer at some point prefers full scans. It depends on your data, your query and configuration. So on read-heavy load you basically lose nothing

1) Postgres optimizer at some point prefers full scans. It depends on your data, your query and configuration. So on read-heavy load you basically lose nothing by adding all appropriate indexes from the get-go. Overhead having index on small tables is small. 2) If your load is write-heavy, you should consider trade-offs. Yes, full scans are sometimes your friends. Interesting thing to notice here that write amplification is basically same even if table is small.