One of the elementary value type supported by db.
This trait is to help with the committing of the transaction for which
the db object should be provided for serialization.
The difference between this trait and KeyValueDbTraitRead is that, the type
which implements KeyValueDbTraitRead may use lock to serialize the reads,
which is not necessarily a multi reader.
These special get methods are provided for db like sqlite, where concurrency
can only be achieved by opening a separate connection, otherwise
lock is required for concurrent read.