/** Variant of {@link #trimFields(RelNode, BitSet, Set)} for {@link SortRel}. */
public TrimResult trimFields(SortRel sort, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
final RelDataType rowType = sort.getRowType();
final int fieldCount = rowType.getFieldCount();
final RelCollation collation = sort.getCollation();
final RelNode input = sort.getChild();
// We use the fields used by the consumer, plus any fields used as sort
// keys.
BitSet inputFieldsUsed = (BitSet) fieldsUsed.clone();
for (RelFieldCollation field : collation.getFieldCollations()) {
inputFieldsUsed.set(field.getFieldIndex());
}
// Create input with trimmed columns.
final Set<RelDataTypeField> inputExtraFields = Collections.emptySet();
TrimResult trimResult = trimChild(sort, input, inputFieldsUsed, inputExtraFields);
RelNode newInput = trimResult.left;
final Mapping inputMapping = trimResult.right;
// If the input is unchanged, and we need to project all columns,
// there's nothing we can do.
if (newInput == input && inputMapping.isIdentity() && fieldsUsed.cardinality() == fieldCount) {
return new TrimResult(sort, Mappings.createIdentity(fieldCount));
}
final SortRel newSort =
sort.copy(sort.getTraitSet(), newInput, RexUtil.apply(inputMapping, collation));
assert newSort.getClass() == sort.getClass();
// The result has the same mapping as the input gave us. Sometimes we
// return fields that the consumer didn't ask for, because the filter
// needs them for its condition.
return new TrimResult(newSort, inputMapping);
}
/** Converts a collation to an ORDER BY item. */
public SqlNode toSql(RelFieldCollation collation) {
SqlNode node = field(collation.getFieldIndex());
switch (collation.getDirection()) {
case DESCENDING:
case STRICTLY_DESCENDING:
node = SqlStdOperatorTable.DESC.createCall(POS, node);
}
switch (collation.nullDirection) {
case FIRST:
node = SqlStdOperatorTable.NULLS_FIRST.createCall(POS, node);
break;
case LAST:
node = SqlStdOperatorTable.NULLS_LAST.createCall(POS, node);
break;
}
return node;
}
/**
* Creates a sorter.
*
* @param cluster Cluster this relational expression belongs to
* @param traits Traits
* @param child input relational expression
* @param collation array of sort specifications
* @param offset Expression for number of rows to discard before returning first row
* @param fetch Expression for number of rows to fetch
*/
public SortRel(
RelOptCluster cluster,
RelTraitSet traits,
RelNode child,
RelCollation collation,
RexNode offset,
RexNode fetch) {
super(cluster, traits, child);
this.collation = collation;
this.offset = offset;
this.fetch = fetch;
assert traits.containsIfApplicable(collation) : "traits=" + traits + ", collation=" + collation;
assert !(fetch == null && offset == null && collation.getFieldCollations().isEmpty())
: "trivial sort";
ImmutableList.Builder<RexNode> builder = ImmutableList.builder();
for (RelFieldCollation field : collation.getFieldCollations()) {
int index = field.getFieldIndex();
builder.add(cluster.getRexBuilder().makeInputRef(child, index));
}
fieldExps = builder.build();
}