EXTENSIBLE STREAMS ON DATA SOURCES

The subject technology determines, using a stream object provided by a network-based database system separate from an external system, a set of offsets of each shard of a set of shards, the set of offsets being determined by executing a user defined function (UDF) included in the stream object, the stream object and the UDF being implemented in a particular programming language different than a database query language. The subject technology identifies an operation to perform on the set of shards. The subject technology, based on the set of shards and the set of offsets, performs, using the UDF included in the stream object, the operation on an external data source hosted by the external system. The subject technology increments a property indicating a different version of the stream object after performing the operation on the external data source, the property being included in the stream object.