Target [] targets = ProjectionPushDownRule.buildGroupByTarget(groupbyNode, null,
aggEvalNames.toArray(new String[aggEvalNames.size()]));
groupbyNode.setTargets(targets);
// this inserted group-by node doesn't pass through preprocessor. So manually added.
block.registerNode(groupbyNode);
postHook(context, stack, null, groupbyNode);
return groupbyNode;
}
/*===============================================================================================