@Override
    public void update(ComplexEventChunk<StateEvent> updatingEventChunk, Object storeEvents,
                       InMemoryCompiledUpdateSet compiledUpdateSet) {

        updatingEventChunk.reset();
        while (updatingEventChunk.hasNext()) {
            StateEvent updatingEvent = updatingEventChunk.next();

            StreamEvent streamEvents = collectionExecutor.find(updatingEvent, (IndexedEventHolder) storeEvents, null);
            if (streamEvents != null) {
                ComplexEventChunk<StreamEvent> foundEventChunk = new ComplexEventChunk<>();
                foundEventChunk.add(streamEvents);
                update((IndexedEventHolder) storeEvents, compiledUpdateSet, updatingEvent, foundEventChunk);
            }
        }
    }
Operator which is related to non-indexed In-memory table operations.
modules/siddhi-core/src/main/java/io/siddhi/core/util/collection/operator/IndexOperator.java