NAME

       mongoc_collection_watch - mongoc_collection_watch()

SYNOPSIS

          mongoc_change_stream_t*
          mongoc_collection_watch (const mongoc_collection_t *coll,
                                   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 collection. 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

       • coll: A mongoc_collection_t specifying the collection 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_client_watch

          mongoc_database_watch

AUTHOR

       MongoDB, Inc

COPYRIGHT

       2017-present, MongoDB, Inc