A big problem with versions of MongoDB prior to 4.4 is that the following commands error out if an index build (https://docs.mongodb.com/master/core/index-creation/#index-builds-on-populated-collections) operation is in progress:
- db.dropDatabase()
- db.collection.drop()
- db.collection.dropIndexes()
In MongoDB 4.4, when this happens, an attempt to force the in-progress index build operation is made. If successful, the index build is halted, and the drop*() operation continues without error. In the case of a drop*() performed on a replica set, the abort attempt is made on the primary. Once the primary commits to the abort, it then synchronizes to the secondaries.
