State Warming Part #3 - Persistent Filter Chains

[softwareplumber]

Bloom filters per se have a couple of disadvantages in our context:

• operations such as intersection require that the bloom filters be the same size
• sparsely populated bloom filters are not a particularly bandwidth-efficient way to transfer information (although: compression?)
• one cannot begin using a bloom filter until it is fully transferred or loaded (contrast: one can read the first item in a list as soon as it is transferred)
• If persistent, any update requires that the entire bloom be written to persistent storage

A list of fixed-size blooms (aka filter chain) might have several advantages, not least that chains of different lengths can be intersected (although efficiency degrades quite quickly as the number of filters in in both chains become larger). The chain can also be incrementally persisted. Thus, propose filter chains as a way of persisting information about a block store which can be leveraged to rapidly 'warm' a car mirror session when cold calling.

ETA: 2024-06-30