next.js

863a0ada - turbo-persistence: add key-value tombstones for MultiValue families (#96929)

turbo-persistence: add key-value tombstones for MultiValue families (#96929) Add a new `tombstone` format to the persistence layer so we can delete key-value pairs out of MultiValued tables This is in service of the upcoming GC support, but also fills a basic API gap in the db. To delete a key-value-pair you need to call `value_delete` and currently the values are limited to only those that are able to be stored inline in key blocks. This is a non-trivial limitation but it fits our current usecase, and makes the compaction/query algorithms a bit simpler (don't need to 'resolve' values) One non-trivial complexity was maintaining the 'FixedLayout' block optimization for a mix of tombstones and values, so now we support a slightly different mode where all keys have the same length but possibly different types. Finally, this branch solves a problem with deleting tombstones. Tombstones 'shadow' older values and allow us to drop them during compaction. With GC getting ready to start writing tombstones the risk becomes 'when can we delete a tombstone! This is solved probabilistically using the amqf filters, during compaction we drop tombstones if they could not possibly match anything in an older SST. Without this, tombstones in the TaskCache table would fill up over time.