Stream Clause
The stream clause is used for continuous queries only. It is used within a from
clause.
See Stream Policy for details on how a window is defined.
Use of Accept:New and Accept:All
Events and concepts (entities) can be deleted by rules. By default (accept: all
), if a continuous query has already seen an entity before, then it will expect a delete or modify notification from the cache cluster. Therefore the query must keep track of such things.
However, if you specify the accept: new
clause, then the continuous query does not have to track such things, and the memory footprint of the query is reduced.
The accept:n
ew
clause is required for event stream processing (ESP) queries. See Event Stream Processing (ESP) Queries.
Use of Emit: New and Emit: Dead
The emit
keyword determines whether the query is evaluated when an entity enters the window (emit : new
) or when an entity leaves the window (emit : dead
).
The default value is emit : new
.
For examples showing usage, see the following: