Description:
This patch exposes a new zstd option for https://docs.mongodb.com/manual/reference/program/mongod/#cmdoption-mongod-wiredtigerjournalcompressor and https://docs.mongodb.com/manual/reference/program/mongod/#cmdoption-mongod-wiredtigercollectionblockcompressor
Creating new collections while using --wiredTigerCollectionBlockCompressor on a 4.2 binary will lock a 4.0 binary from being able to start up on the data files. Downgrading will require a resync.
Starting a 4.2 mongod binary with --wiredTigerJournalCompressor=zstd can downgrade to a 4.0 binary after a clean shutdown. Recovering from an unclean shutdown will require a 4.2 binary.
Engineering Ticket Description:
Zstd is available in WiredTiger but cannot be configured as an option in MongoDB. This ticket is to track this functionality