Continuous Queries

A continuous query returns results throughout its lifetime, as changes occur. When nothing changes, the query waits.

  • Overview of Continuous Queries
    When used in a query agent deployed in a TIBCO BusinessEvents cluster, continuous queries listen to and process the data stream of notifications sent from the cache. Notifications are sent when entities are added to, modified or deleted from the cache.
  • Working With Implicit Windows
    Implicit windows are created when the continuous query does not have an explicit policy (window) clause.
  • Working With Sliding Tumbling and Time Windows
    Sliding, tumbling, and time windows are explicit windows. In an explicit window, the lifecycle of an entity in a window is determined either by a specified duration of the entity in the window, or by setting a maximum number of entities that can be in the window at any time.
  • Sliding Window Examples (Cache Queries)
    A sliding window policy maintains a queue of a specified size, into which entities flow. When the queue is full and a new entity arrives, the oldest entity in the queue is removed from the window (FIFO).
  • Tumbling Window Examples (Cache Queries)
    A tumbling window a specified queue size, specified as a certain number of entities, and empties each time the maximum size is exceeded. Emptying the window completes one cycle. The lifetime of an entity in the window, therefore, is one cycle.
  • Time Window Examples (Cache Queries)
    Time windows use a stream policy that specifies how long an entity remains in the window.