mongoc_write_concern_t3
Usage
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 abstraction
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.
Releases
5 releases since Debian 9 (Stretch); the text changed 4 times.