public static RelDataType createTypeFromProjection(
RelDataType type,
List<String> columnNameList,
RelDataTypeFactory typeFactory,
boolean caseSensitive) {
// If the names in columnNameList and type have case-sensitive differences,
// the resulting type will use those from type. These are presumably more
// canonical.
final List<RelDataTypeField> fields = new ArrayList<RelDataTypeField>(columnNameList.size());
for (String name : columnNameList) {
RelDataTypeField field = type.getField(name, caseSensitive);
fields.add(type.getFieldList().get(field.getIndex()));
}
return typeFactory.createStructType(fields);
}
private List<RelCollation> deduceMonotonicity(SqlValidatorTable table) {
final RelDataType rowType = table.getRowType();
final List<RelCollation> collationList = new ArrayList<RelCollation>();
// Deduce which fields the table is sorted on.
int i = -1;
for (RelDataTypeField field : rowType.getFieldList()) {
++i;
final SqlMonotonicity monotonicity = table.getMonotonicity(field.getName());
if (monotonicity != SqlMonotonicity.NOT_MONOTONIC) {
final RelFieldCollation.Direction direction =
monotonicity.isDecreasing()
? RelFieldCollation.Direction.DESCENDING
: RelFieldCollation.Direction.ASCENDING;
collationList.add(
RelCollationImpl.of(
new RelFieldCollation(
i, direction, RelFieldCollation.NullDirection.UNSPECIFIED)));
}
}
return collationList;
}
/**
* Trims a child relational expression, then adds back a dummy project to restore the fields that
* were removed.
*
* <p>Sounds pointless? It causes unused fields to be removed further down the tree (towards the
* leaves), but it ensure that the consuming relational expression continues to see the same
* fields.
*
* @param rel Relational expression
* @param input Input relational expression, whose fields to trim
* @param fieldsUsed Bitmap of fields needed by the consumer
* @return New relational expression and its field mapping
*/
protected TrimResult trimChildRestore(
RelNode rel, RelNode input, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
TrimResult trimResult = trimChild(rel, input, fieldsUsed, extraFields);
if (trimResult.right.isIdentity()) {
return trimResult;
}
final RelDataType rowType = input.getRowType();
List<RelDataTypeField> fieldList = rowType.getFieldList();
final List<RexNode> exprList = new ArrayList<RexNode>();
final List<String> nameList = rowType.getFieldNames();
RexBuilder rexBuilder = rel.getCluster().getRexBuilder();
assert trimResult.right.getSourceCount() == fieldList.size();
for (int i = 0; i < fieldList.size(); i++) {
int source = trimResult.right.getTargetOpt(i);
RelDataTypeField field = fieldList.get(i);
exprList.add(
source < 0
? rexBuilder.makeZeroLiteral(field.getType())
: rexBuilder.makeInputRef(field.getType(), source));
}
RelNode project = CalcRel.createProject(trimResult.left, exprList, nameList);
return new TrimResult(project, Mappings.createIdentity(fieldList.size()));
}
/**
* Variant of {@link #trimFields(RelNode, BitSet, Set)} for {@link org.eigenbase.rel.ValuesRel}.
*/
public TrimResult trimFields(
ValuesRel values, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
final RelDataType rowType = values.getRowType();
final int fieldCount = rowType.getFieldCount();
// If they are asking for no fields, we can't give them what they want,
// because zero-column records are illegal. Give them the last field,
// which is unlikely to be a system field.
if (fieldsUsed.isEmpty()) {
fieldsUsed = Util.bitSetBetween(fieldCount - 1, fieldCount);
}
// If all fields are used, return unchanged.
if (fieldsUsed.equals(Util.bitSetBetween(0, fieldCount))) {
Mapping mapping = Mappings.createIdentity(fieldCount);
return new TrimResult(values, mapping);
}
List<List<RexLiteral>> newTuples = new ArrayList<List<RexLiteral>>();
for (List<RexLiteral> tuple : values.getTuples()) {
List<RexLiteral> newTuple = new ArrayList<RexLiteral>();
for (int field : Util.toIter(fieldsUsed)) {
newTuple.add(tuple.get(field));
}
newTuples.add(newTuple);
}
final Mapping mapping = createMapping(fieldsUsed, fieldCount);
RelDataType newRowType =
values
.getCluster()
.getTypeFactory()
.createStructType(Mappings.apply3(mapping, rowType.getFieldList()));
final ValuesRel newValues = new ValuesRel(values.getCluster(), newRowType, newTuples);
return new TrimResult(newValues, mapping);
}
/** Variant of {@link #trimFields(RelNode, BitSet, Set)} for {@link ProjectRel}. */
public TrimResult trimFields(
ProjectRel project, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
final RelDataType rowType = project.getRowType();
final int fieldCount = rowType.getFieldCount();
final RelNode input = project.getChild();
final RelDataType inputRowType = input.getRowType();
// Which fields are required from the input?
BitSet inputFieldsUsed = new BitSet(inputRowType.getFieldCount());
final Set<RelDataTypeField> inputExtraFields = new LinkedHashSet<RelDataTypeField>(extraFields);
RelOptUtil.InputFinder inputFinder =
new RelOptUtil.InputFinder(inputFieldsUsed, inputExtraFields);
for (Ord<RexNode> ord : Ord.zip(project.getProjects())) {
if (fieldsUsed.get(ord.i)) {
ord.e.accept(inputFinder);
}
}
// Create input with trimmed columns.
TrimResult trimResult = trimChild(project, 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 && fieldsUsed.cardinality() == fieldCount) {
return new TrimResult(project, Mappings.createIdentity(fieldCount));
}
// Some parts of the system can't handle rows with zero fields, so
// pretend that one field is used.
if (fieldsUsed.cardinality() == 0) {
final Mapping mapping = Mappings.create(MappingType.InverseSurjection, fieldCount, 1);
final RexLiteral expr =
project.getCluster().getRexBuilder().makeExactLiteral(BigDecimal.ZERO);
RelDataType newRowType =
project
.getCluster()
.getTypeFactory()
.createStructType(
Collections.singletonList(expr.getType()), Collections.singletonList("DUMMY"));
ProjectRel newProject =
new ProjectRel(
project.getCluster(),
project.getCluster().traitSetOf(RelCollationImpl.EMPTY),
newInput,
Collections.<RexNode>singletonList(expr),
newRowType,
project.getFlags());
return new TrimResult(newProject, mapping);
}
// Build new project expressions, and populate the mapping.
List<RexNode> newProjectExprList = new ArrayList<RexNode>();
final RexVisitor<RexNode> shuttle = new RexPermuteInputsShuttle(inputMapping, newInput);
final Mapping mapping =
Mappings.create(MappingType.InverseSurjection, fieldCount, fieldsUsed.cardinality());
for (Ord<RexNode> ord : Ord.zip(project.getProjects())) {
if (fieldsUsed.get(ord.i)) {
mapping.set(ord.i, newProjectExprList.size());
RexNode newProjectExpr = ord.e.accept(shuttle);
newProjectExprList.add(newProjectExpr);
}
}
final RelDataType newRowType =
project
.getCluster()
.getTypeFactory()
.createStructType(Mappings.apply3(mapping, rowType.getFieldList()));
final List<RelCollation> newCollations =
RexUtil.apply(inputMapping, project.getCollationList());
final RelNode newProject;
if (RemoveTrivialProjectRule.isIdentity(
newProjectExprList, newRowType, newInput.getRowType())) {
// The new project would be the identity. It is equivalent to return
// its child.
newProject = newInput;
} else {
newProject =
new ProjectRel(
project.getCluster(),
project
.getCluster()
.traitSetOf(
newCollations.isEmpty() ? RelCollationImpl.EMPTY : newCollations.get(0)),
newInput,
newProjectExprList,
newRowType,
project.getFlags());
assert newProject.getClass() == project.getClass();
}
return new TrimResult(newProject, mapping);
}
