Not materialising the persistent queue

Very often a persistent queue on a producer isn't directly materialised, because a direct representation is inefficient.

For example, CEDA doesn’t materialise persistent queues of operations even though it's natural to think of the operations on the database as being produced sequentially on that site. Instead a representation is used that is more space efficient, and enables more efficient algorithms for propagating, transforming and applying operations.

The CEDA implementation makes use of the fact that:

• Operations can be organised by the objects they apply to, or by the producer that produced them
• Assignment operations tend to mask previous operations
• Delta operations can be merged
• Insert/delete operations on strings can be merged