Introduces two options for mod_roster and mod_roster_odbc:
- {versioning, true | false} Enable or disable roster versioning on ejabberd.
- {store_current_id, true | false} If true, the current roster version is stored on DB (internal or odbc). Otherwise it is calculated on the fly each time.
Performance:
Setting store_current_id to true should help in reducing the load for both ejabberd and the DB.
Details:
If store_current_id is false, the roster version is a hash of the entire roster. If store_current_id is true, the roster version is a hash, but of the current time
(this has to do with transactional semantics; we need to perform both the roster update and the version update on the same transaction, but we don't
have the entire roster when we are changing a single item on DB. Loading it there requires significant changes to be introduced, so I opted for this simpler approach).
In either case, there is no difference for the clients, the roster version ID is opaque.
IMPORTANT:
mod_shared_roster is not compatible with the option 'store_current_id'. Shared roster and roster versioning can be both enabled, but store_current_id MUST be set to false.
SVN Revision: 2428
