What should primary keys be?
The Proposed Server API page asks "What do we want keys to be?".
This page collects and evaluates the options.
User-allocated variable-length or long fixed-length keys
- These longer keys must be passed around in requests.
- The master needs a hash table.
- There is some feature overlap with indexes. Now you need an extremely fast "primary index" on the master to look up objects.
User-allocated 64-bit keys
- I think there's a consensus that this is not a large enough space to be used as a reasonable hash value, so the only real use case is ICQ.