Use the generic derived stream, derived window, and derived delta stream shapes to create more complex continuous queries in the Visual editor than the ones you can create with the simple query shapes.
A derived stream, derived window, or derived delta stream takes input from another stream or window, rather than directly from an adapter, and applies a continuous query to it. All of the simple queries in the Visual editor are a type of derived stream or derived window.
For example, to create a continuous query that applies both a set of join conditions and a pattern matching expression, use a generic derived window.
Choose the shape type according to your input, output, and retention requirements for data, and for preserving insert, update, and delete operations.
| Shape | Input | Output | Retains state | Preserves inserts, updates, and deletes |
|---|---|---|---|---|
| Derived Stream | Another stream | Stream | no | no |
| Derived Window | Another stream or window | Window | As defined in Keep policy (default is keep all rows) | yes Note: In order to derive a window from a stream, a GROUP BY
clause must be included in the query.
|
| Derived Delta Stream | Another window or delta stream | Stream | no | yes Note: A delta stream only accepts either inserts or deletes.
|