Mongodb Read Concern. Web read concern local and transactions. Snapshot read concern (and mvcc in general, which it is an implementation of) is a concurrency mechanism but not a locking mechanism.
Web mongodb drivers updated for mongodb 3.2 or later support specifying read concern. Starting in mongodb 4.4, replica sets and sharded clusters support setting a global. Web for example, if, in a causally consistent session, you issue a write with majority write concern followed by a read that reads from a secondary (i.e. Web to set the read concern for transactions, see transactions and read concern. Web default mongodb read concerns/write concerns. You set the read concern at the transaction level, not at the individual operation level. Web mongodb drivers updated for mongodb 3.2 or later support specifying read concern. Starting in mongodb 4.4, replica sets and sharded clusters support setting a global. Specifically, mongodb uses the following formula to determine the default write concern: Web read concern local and transactions.
Web mongodb drivers updated for mongodb 3.2 or later support specifying read concern. For a sharded cluster , available. (string) the read concern level specifies the level of isolation for read operations. Web mongodb drivers updated for mongodb 3.2 or later support specifying read concern. A query with read concern available returns data from the instance with no guarantee that the data has been written to a majority of the replica set. Web to set the read concern for transactions, see transactions and read concern. Possible read concern levels are: This is the default read concern level for read operations against the primary and. Starting in mongodb 4.4, you can create collections and indexes inside a transaction. Snapshot read concern (and mvcc in general, which it is an implementation of) is a concurrency mechanism but not a locking mechanism. Web read concern available is the default for reads against secondaries if the reads are not associated with causally consistent sessions.
