/** 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);
}
private Mapping createMapping(BitSet fieldsUsed, int fieldCount) {
final Mapping mapping =
Mappings.create(MappingType.InverseSurjection, fieldCount, fieldsUsed.cardinality());
int i = 0;
for (int field : Util.toIter(fieldsUsed)) {
mapping.set(field, i++);
}
return mapping;
}
public Boolean areColumnsUnique(ProjectRelBase rel, BitSet columns, boolean ignoreNulls) {
// ProjectRel maps a set of rows to a different set;
// Without knowledge of the mapping function(whether it
// preserves uniqueness), it is only safe to derive uniqueness
// info from the child of a project when the mapping is f(a) => a.
//
// Also need to map the input column set to the corresponding child
// references
List<RexNode> projExprs = rel.getProjects();
BitSet childColumns = new BitSet();
for (int bit : BitSets.toIter(columns)) {
RexNode projExpr = projExprs.get(bit);
if (projExpr instanceof RexInputRef) {
childColumns.set(((RexInputRef) projExpr).getIndex());
} else if (projExpr instanceof RexCall && ignoreNulls) {
// If the expression is a cast such that the types are the same
// except for the nullability, then if we're ignoring nulls,
// it doesn't matter whether the underlying column reference
// is nullable. Check that the types are the same by making a
// nullable copy of both types and then comparing them.
RexCall call = (RexCall) projExpr;
if (call.getOperator() != SqlStdOperatorTable.CAST) {
continue;
}
RexNode castOperand = call.getOperands().get(0);
if (!(castOperand instanceof RexInputRef)) {
continue;
}
RelDataTypeFactory typeFactory = rel.getCluster().getTypeFactory();
RelDataType castType = typeFactory.createTypeWithNullability(projExpr.getType(), true);
RelDataType origType = typeFactory.createTypeWithNullability(castOperand.getType(), true);
if (castType.equals(origType)) {
childColumns.set(((RexInputRef) castOperand).getIndex());
}
} else {
// If the expression will not influence uniqueness of the
// projection, then skip it.
continue;
}
}
// If no columns can affect uniqueness, then return unknown
if (childColumns.cardinality() == 0) {
return null;
}
return RelMetadataQuery.areColumnsUnique(rel.getChild(), childColumns, ignoreNulls);
}
/** Variant of {@link #trimFields(RelNode, BitSet, Set)} for {@link FilterRel}. */
public TrimResult trimFields(
FilterRel filter, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
final RelDataType rowType = filter.getRowType();
final int fieldCount = rowType.getFieldCount();
final RexNode conditionExpr = filter.getCondition();
final RelNode input = filter.getChild();
// We use the fields used by the consumer, plus any fields used in the
// filter.
BitSet inputFieldsUsed = (BitSet) fieldsUsed.clone();
final Set<RelDataTypeField> inputExtraFields = new LinkedHashSet<RelDataTypeField>(extraFields);
RelOptUtil.InputFinder inputFinder =
new RelOptUtil.InputFinder(inputFieldsUsed, inputExtraFields);
conditionExpr.accept(inputFinder);
// Create input with trimmed columns.
TrimResult trimResult = trimChild(filter, 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(filter, Mappings.createIdentity(fieldCount));
}
// Build new project expressions, and populate the mapping.
final RexVisitor<RexNode> shuttle = new RexPermuteInputsShuttle(inputMapping, newInput);
RexNode newConditionExpr = conditionExpr.accept(shuttle);
final FilterRel newFilter = new FilterRel(filter.getCluster(), newInput, newConditionExpr);
assert newFilter.getClass() == filter.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(newFilter, inputMapping);
}
/** 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);
}
public Boolean areColumnsUnique(JoinRelBase rel, BitSet columns, boolean ignoreNulls) {
if (columns.cardinality() == 0) {
return false;
}
final RelNode left = rel.getLeft();
final RelNode right = rel.getRight();
// Divide up the input column mask into column masks for the left and
// right sides of the join
BitSet leftColumns = new BitSet();
BitSet rightColumns = new BitSet();
int nLeftColumns = left.getRowType().getFieldCount();
for (int bit : BitSets.toIter(columns)) {
if (bit < nLeftColumns) {
leftColumns.set(bit);
} else {
rightColumns.set(bit - nLeftColumns);
}
}
// If the original column mask contains columns from both the left and
// right hand side, then the columns are unique if and only if they're
// unique for their respective join inputs
Boolean leftUnique = RelMetadataQuery.areColumnsUnique(left, leftColumns, ignoreNulls);
Boolean rightUnique = RelMetadataQuery.areColumnsUnique(right, rightColumns, ignoreNulls);
if ((leftColumns.cardinality() > 0) && (rightColumns.cardinality() > 0)) {
if ((leftUnique == null) || (rightUnique == null)) {
return null;
} else {
return leftUnique && rightUnique;
}
}
// If we're only trying to determine uniqueness for columns that
// originate from one join input, then determine if the equijoin
// columns from the other join input are unique. If they are, then
// the columns are unique for the entire join if they're unique for
// the corresponding join input, provided that input is not null
// generating.
final JoinInfo joinInfo = rel.analyzeCondition();
if (leftColumns.cardinality() > 0) {
if (rel.getJoinType().generatesNullsOnLeft()) {
return false;
}
Boolean rightJoinColsUnique =
RelMetadataQuery.areColumnsUnique(right, joinInfo.rightSet(), ignoreNulls);
if ((rightJoinColsUnique == null) || (leftUnique == null)) {
return null;
}
return rightJoinColsUnique && leftUnique;
} else if (rightColumns.cardinality() > 0) {
if (rel.getJoinType().generatesNullsOnRight()) {
return false;
}
Boolean leftJoinColsUnique =
RelMetadataQuery.areColumnsUnique(left, joinInfo.leftSet(), ignoreNulls);
if ((leftJoinColsUnique == null) || (rightUnique == null)) {
return null;
}
return leftJoinColsUnique && rightUnique;
}
throw new AssertionError();
}
