[jakewins]

It is, arguably, deployed at scale, if you squint and call it delta compression. The reason its not more widely used is there are drawbacks. Updates can be more expensive, for instance: what was a single-key change perhaps blew up a 1000 key "line" and now all those keys need reshuffling. You also see more muted returns because generally keys in indexes point to something, so compressing the keys creates complexity in how you map each key to its value or reference. Compared to a solution that stores keys close to their values, a solution that packs keys together gets poor cache locality for resolving the values, and may need mapping tables.

Basically, delta compression is used all over the place, but it isnt a silver bullet.