MongoTimeouts

How long a store's calls to MongoDB may take (the driver's client-side operation timeout, timeoutMS): without one, a reply lost on the way (a failover, a proxy) blocks its caller forever, the driver's socket reads having no timeout. Every call of the log and the stores has OPERATION unless its store sets another (wow.mongo.operation-timeout); an append has its own, shorter (wow.mongo.append-timeout); the schema's commands (format records, indexes, sharding) have DDL, as an index built over a large collection may take minutes. A call that times out fails as transient (MongoFailures): a write's outcome is then unknown. The queries keep their own budget (maxTimeMS).