public List<Double> averageColumnSizes(Values rel, RelMetadataQuery mq) {
final List<RelDataTypeField> fields = rel.getRowType().getFieldList();
final ImmutableList.Builder<Double> list = ImmutableList.builder();
for (int i = 0; i < fields.size(); i++) {
RelDataTypeField field = fields.get(i);
double d;
if (rel.getTuples().isEmpty()) {
d = averageTypeValueSize(field.getType());
} else {
d = 0;
for (ImmutableList<RexLiteral> literals : rel.getTuples()) {
d += typeValueSize(field.getType(), literals.get(i).getValue());
}
d /= rel.getTuples().size();
}
list.add(d);
}
return list.build();
}
public Double getDistinctRowCount(Values rel, ImmutableBitSet groupKey, RexNode predicate) {
if (predicate == null || predicate.isAlwaysTrue()) {
if (groupKey.isEmpty()) {
return 1D;
}
}
Double selectivity = RelMdUtil.guessSelectivity(predicate);
// assume half the rows are duplicates
Double nRows = rel.getRows() / 2;
return RelMdUtil.numDistinctVals(nRows, nRows * selectivity);
}
public Double getMaxRowCount(Values values, RelMetadataQuery mq) {
// For Values, the maximum row count is the actual row count.
// This is especially useful if Values is empty.
return (double) values.getTuples().size();
}
