NAME

       mongoc_client_watch - mongoc_client_watch()

SYNOPSIS

          mongoc_change_stream_t*
          mongoc_client_watch (mongoc_client_t *client,
                               const bson_t *pipeline,
                               const bson_t *opts) BSON_GNUC_WARN_UNUSED_RESULT;

       A  helper  function  to create a change stream. It is preferred to call this function over
       using a raw aggregation to create a change stream.

       This function uses the read preference and read concern  of  the  client.  If  the  change
       stream  needs  to re-establish connection, the same read preference will be used. This may
       happen if the change stream encounters a resumable error.

       WARNING:
          A change stream is only supported with majority read concern.

       This function is considered a retryable read operation.  Upon a transient error (a network
       error, errors due to replica set failover, etc.) the operation is safely retried once.  If
       retryreads is false in the URI (see mongoc_uri_t) the retry behavior does not apply.

PARAMETERS

       • db: A mongoc_client_t specifying the client which the change stream listens to.

       • pipeline: A bson_t representing an aggregation pipeline appended to the  change  stream.
         This may be an empty document.

       • opts: A bson_t containing change stream options.

       opts may be NULL or a BSON document with additional command options:

       • batchSize:  An  int32  representing number of documents requested to be returned on each
         call to mongoc_change_stream_next

       • resumeAfter: A Document representing the logical starting point of  the  change  stream.
         The  result  of  mongoc_change_stream_get_resume_token() or the _id field  of any change
         received from a change stream can be used here. This option is mutually  exclusive  with
         startAfter and startAtOperationTime.

       • startAfter:  A  Document  representing  the logical starting point of the change stream.
         Unlike resumeAfter, this can resume  notifications  after  an  "invalidate"  event.  The
         result  of  mongoc_change_stream_get_resume_token()  or  the  _id  field   of any change
         received from a change stream can be used here.  This option is mutually exclusive  with
         resumeAfter and startAtOperationTime.

       • startAtOperationTime: A Timestamp. The change stream only provides changes that occurred
         at or after the specified timestamp. Any command run against the server will  return  an
         operation time that can be used here. This option is mutually exclusive with resumeAfter
         and startAfter.

       • maxAwaitTimeMS:  An  int64  representing  the  maximum  amount  of  time   a   call   to
         mongoc_change_stream_next will block waiting for data

       • fullDocument:  A  UTF-8  string.  Set this option to "updateLookup" to direct the change
         stream cursor to lookup the most current  majority-committed  version  of  the  document
         associated to an update change stream event.

RETURNS

       A     newly    allocated    mongoc_change_stream_t    which    must    be    freed    with
       mongoc_change_stream_destroy when no longer in use. The returned mongoc_change_stream_t is
       never    NULL.    If    there    is    an    error,    it    can    be    retrieved   with
       mongoc_change_stream_error_document, and  subsequent  calls  to  mongoc_change_stream_next
       will return false.

       SEE ALSO:
          mongoc_database_watch

          mongoc_collection_watch

AUTHOR

       MongoDB, Inc

COPYRIGHT

       2017-present, MongoDB, Inc