} else {
if (gbInfo.isChangedToSerialAggregate()) {
assert(root instanceof ReceivePlanNode);
aggNode = new AggregatePlanNode();
} else if (gbInfo.isChangedToPartialAggregate()) {
aggNode = new PartialAggregatePlanNode(gbInfo.m_coveredGroupByColumns);
} else {
aggNode = new HashAggregatePlanNode();
}
topAggNode = new HashAggregatePlanNode();