@Override
public RelOptCost computeSelfCost(RelOptPlanner planner) {
// Higher cost if rows are wider discourages pushing a project through a
// sort.
double rowCount = RelMetadataQuery.getRowCount(this);
double bytesPerRow = getRowType().getFieldCount() * 4;
return planner.getCostFactory().makeCost(Util.nLogN(rowCount) * bytesPerRow, rowCount, 0);
}
