com.espertech.esper.client.hook
Interface VirtualDataWindowLookup

public interface VirtualDataWindowLookup

Represents a lookup strategy object that an EPL statement that queries a virtual data window obtains to perform read operations into the virtual data window.

An instance is associated to each EPL statement querying (join, subquery, on-action etc.) the virtual data window.

Optimally an implementation returns only those rows matching the complete lookup context filtered field information.*

It is legal for an implementation to return rows that are not matching lookup context filter field information. Such rows are removed by where-clause criteria, when provided.

Method Summary

java.util.Set<EventBean>

lookup(java.lang.Object[] keys, EventBean[] eventsPerStream) Invoked by an EPL statement that queries a virtual data window to perform a lookup.

Method Detail

lookup

java.util.Set<EventBean> lookup(java.lang.Object[] keys,
                                EventBean[] eventsPerStream)

Invoked by an EPL statement that queries a virtual data window to perform a lookup.

Keys passed are the actual query lookup values. For range lookups, the key passed is an instance of VirtualDataWindowKeyRange.

Key values follow VirtualDataWindowLookupContext.

EventsPerStream contains the events participating in the subquery or join. It is not necessary to use eventsPerStream and the events are provided for additional information. Please consider eventsPerStream for Esper internal use.

Parameters:

keys - lookup values

eventsPerStream - input events for the lookup

Returns:

set of events