Comment by benwilber0
2 years ago
Maybe? idk. Not in Postgres. The default index is a B-Tree. A hash-based index would be terrible for disk-seeking, in any case.
2 years ago
Maybe? idk. Not in Postgres. The default index is a B-Tree. A hash-based index would be terrible for disk-seeking, in any case.
https://www.postgresql.org/docs/current/indexes-types.html#I...
Postgres has it, but it didn't used to, and it's still got caveats.
Beyond Postgres, indexing random values is fundamentally harder than indexing sorted ones, whether you've got a hashmap or btree or something else. The often-cited O(1) lookup complexity of a hashmap assumes everything easily fits in uniform-access memory.
Probably the worst PK index of all time. There's a reason why it's barely ever used.