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

1.27.5                                            Aug 06, 2024               MONGOC_SESSION_OPTS_SET_SNAPSHOT(3)