Write Concern abstraction

SYNOPSIS

mongoc_write_concern_t tells the driver what level of acknowledgement to await from the server. The default, MONGOC_WRITE_CONCERN_W_DEFAULT, is right for the great majority of applications.

You can specify a write concern on connection objects, database objects, collection objects, or per-operation. Data-modifying operations typically use the write concern of the object they operate on, and check the server response for a write concern error or write concern timeout. For example, mongoc_collection_drop_index() uses the collection's write concern, and a write concern error or timeout in the response is considered a failure.

Exceptions to this principle are the generic command functions:

mongoc_client_command()
mongoc_client_command_simple()
mongoc_database_command()
mongoc_database_command_simple()
mongoc_collection_command()
mongoc_collection_command_simple()

These generic command functions do not automatically apply a write concern, and they do not check the server response for a write concern error or write concern timeout.

See Write Concern on the MongoDB website for more information.

WRITE CONCERN LEVELS

Set the write concern level with mongoc_write_concern_set_w().

MONGOC_WRITE_CONCERN_W_DEFAULT (1)	By default, writes block awaiting acknowledgement from MongoDB. Acknowledged write concern allows clients to catch network, duplicate key, and other errors.
MONGOC_WRITE_CONCERN_W_UNACKNOWLEDGED (0)	With this write concern, MongoDB does not acknowledge the receipt of write operation. Unacknowledged is similar to errors ignored; however, mongoc attempts to receive and handle network errors when possible.
MONGOC_WRITE_CONCERN_W_MAJORITY (majority)	Block until a write has been propagated to a majority of the nodes in the replica set.
n	Block until a write has been propagated to at least n nodes in the replica set.

DEPRECATIONS

The write concern MONGOC_WRITE_CONCERN_W_ERRORS_IGNORED (value -1) is a deprecated synonym for MONGOC_WRITE_CONCERN_W_UNACKNOWLEDGED (value 0), and will be removed in the next major release.

mongoc_write_concern_set_fsync() is deprecated.

AUTHOR

MongoDB, Inc

COPYRIGHT

2009-present, MongoDB, Inc.