CQL is a powerful language for performing event processing. In this chapter, you learned the foundations of CEP, one important aspect of which is the difference between streams and relations. You can now convert a stream to a relation by applying window operations. CQL supports several useful Window operators such as tuple-based windows, time-based windows, and partitioned windows. You can also convert a relation to a stream by using the ISTREAM
, DSTREAM
, and RSTREAM
operations.
When using relations, you can apply most SQL operations, such as joins, aggregations, and ordering. The main difference is that these operations are executed in a continuous form.
We also learned how CQL native types are similar to that of Java and the RDBMS, and provide several functions for casting.
Finally, we looked into how CQL interprets time and different timing models supported, such as system time-stamped and application time-stamped streams.
In the next chapter we will be moving onto how to manage,...