mongoc_session_opts_set_causal_consistency

mongoc_session_opts_set_causal_consistency()

Synopsis

void
mongoc_session_opts_set_causal_consistency (mongoc_session_opt_t *opts,
                                            bool causal_consistency);

Configure causal consistency in a session. If true (the default), each operation in the session will be causally ordered after the previous read or write operation. Set to false to disable causal consistency. See the MongoDB Manual Entry for Causal Consistency.

Unacknowledged writes are not causally consistent. If you execute a write operation with a mongoc_write_concern_t on which you have called mongoc_write_concern_set_w with a value of 0, the write does not participate in causal consistency.

Parameters

Example

mongoc_client_t *client;
mongoc_session_opt_t *session_opts;
mongoc_client_session_t *client_session;
mongoc_collection_t *collection;
bson_t insert_opts = BSON_INITIALIZER;
bson_t *doc;
bson_error_t error;
bool r;

client = mongoc_client_new ("mongodb://example/?appname=session-opts-example");
mongoc_client_set_error_api (client, 2);

session_opts = mongoc_session_opts_new ();
mongoc_session_opts_set_causal_consistency (session_opts, false);
client_session = mongoc_client_start_session (client, session_opts, &error);
mongoc_session_opts_destroy (session_opts);

if (!client_session) {
   fprintf (stderr, "Failed to start session: %s\n", error.message);
   abort ();
}

collection = mongoc_client_get_collection (client, "test", "collection");
doc = BCON_NEW ("_id", BCON_INT32 (1));
r = mongoc_client_session_append (client_session, &insert_opts, NULL);
if (!r) {
   fprintf (stderr, "mongoc_client_session_append failed: %s\n", error.message);
   abort ();
}

r = mongoc_collection_insert_one (
   collection, doc, &insert_opts, NULL /* reply */, &error);

if (!r) {
   fprintf (stderr, "Insert failed: %s\n", error.message);
   abort ();
}

Author

MongoDB, Inc

Info

Apr 09, 2021 1.17.5 libmongoc