NAME

       mongoc_session_opts_set_snapshot - mongoc_session_opts_set_snapshot()

SYNOPSIS

          void
          mongoc_session_opts_set_snapshot (mongoc_session_opt_t *opts,
                                            bool snapshot);

       Configure snapshot reads for a session. If true (false by default), each read operation in
       the session will be sent with a "snapshot"  level  read  concern.  After  the  first  read
       operation  ("find",  "aggregate" or "distinct"), subsequent read operations will read from
       the same point in time as the first read operation. Set to true to enable snapshot  reads.
       See the official documentation for Read Concern "snapshot".

       Snapshot  reads  and  causal consistency are mutually exclusive. Attempting to set both to
       true will result in an error. See mongoc_session_opts_set_causal_consistency().

       Snapshot reads can only be used on MongoDB server version 5.0 and later and cannot be used
       during  a transaction. A write operation in a snapshot-enabled session will also result in
       an error.

PARAMETERS

       • opts: A mongoc_session_opt_t.

       • snapshot: True or false.

EXAMPLE

          mongoc_client_t *client;
          mongoc_session_opt_t *session_opts;
          mongoc_client_session_t *client_session;
          mongoc_collection_t *collection;
          bson_t query_opts = BSON_INITIALIZER;
          bson_t filter = BSON_INITIALIZER;
          bson_t pipeline = BSON_INITIALIZER;

          client = mongoc_client_new ("mongodb://example/?appname=session-opts-example");
          mongoc_client_set_error_api (client, MONGOC_ERROR_API_VERSION_2);

          session_opts = mongoc_session_opts_new ();
          mongoc_session_opts_set_snapshot (session_opts, true);
          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");
          r = mongoc_client_session_append (client_session, &find_opts, &error);
          if (!r) {
             fprintf (stderr, "mongoc_client_session_append failed: %s\n", error.message);
             abort ();
          }

          /* First read operation will set the snapshot time for subsequent reads. */
          cursor = mongoc_collection_find_with_opts (collection, filter, &query_opts, NULL);

          /* Subsequent read operations will automatically read from the same point
           * in time as the first read operation. */
          cursor = mongoc_collection_aggregate (collection, MONGOC_QUERY_NONE, pipeline, &query_opts, NULL);

AUTHOR

       MongoDB, Inc

COPYRIGHT

       2017-present, MongoDB, Inc