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VirtualDataWindowGetLookup Method

Returns the lookup strategy for use by an EPL statement to obtain data.

This method is invoked one or more times at the time an EPL statement is created that performs a subquery, join, on-action or fire-and-forget query against the virtual data window.

The lookup strategy returned is used when the EPL statement for which it was created performs a read-operation against the managed data. Multiple lookup strategies for the same EPL statement are possible for join statements.

The context object passed in is derived from an analysis of the where-clause and lists the unique property names of the event type that are index fields, i.e. fields against which the lookup occurs.

The order of hash and btree properties provided by the context matches the order that lookup values are provided to the lookup strategy.

Namespace:  com.espertech.esper.common.client.hook.vdw
Assembly:  NEsper.Common (in NEsper.Common.dll) Version: 8.0.0.0
Syntax
C#
VirtualDataWindowLookup GetLookup(
	VirtualDataWindowLookupContext desc
)

Parameters

desc
Type: com.espertech.esper.common.client.hook.vdwVirtualDataWindowLookupContext
hash and binary tree (sorted access for ranges) index fields

Return Value

Type: VirtualDataWindowLookup
lookup strategy, or null to veto the statement
See Also