continuously updated materialized views src dest total 1 2 20K sum src dest bytes 1 2 20K • Base streams update relation tables and derived streams update materialized views. • An operator outputs event Boston University 2020 • Base streams update relation tables and derived streams update materialized views. • An operator outputs event streams that describe the changing view computed over the input stream 20K 2 5 32K src dest total 1 2 20K 2 5 32K sum Results as continuously updated materialized views 20 Vasiliki Kalavri | Boston University 2020 src dest bytes 1 2 20K 2 5 32K 1 2 28K src dest

database tables • Continuous queries on data streams • New streams (derived) are defined as virtual views in SQL • Semantics are equivalent to having an append-only table to which new tuples are continuously