currentTuple = this.currentSource.nextTuple();
if (currentTuple == null) {
return;
}
List<?> key = RelationalNode.projectTuple(this.notSortedSource.getExpressionIndexes(), this.currentTuple);
tb = new TupleBrowser(this.index, new CollectionTupleSource(Arrays.asList(key).iterator()), OrderBy.ASC);
}
if (sortedTuple == null) {
sortedTuple = tb.nextTuple();
if (sortedTuple == null) {