Too Long; Didn't Read
The following guide outlines the purpose of each index type available in PostgreSQL. Each index will serve a special purpose and do exactly what is needed. Additional index types that are available on the web include rum, vodka, and, in the future, cognac. Hash indexes have been around for many years, but before Postgres 10.0 it was not advisable to use hash indexes because Postgres had no W.write-ahead logging support for them. In Postgres' new version, Hash indexes are fully logged and are considered to be 100 crash-safe.