/**
* Trims the fields of an input relational expression.
*
* @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 trimChild(
RelNode rel, RelNode input, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
Util.discard(rel);
if (input.getClass().getName().endsWith("MedMdrClassExtentRel")) {
// MedMdrJoinRule cannot handle Join of Project of
// MedMdrClassExtentRel, only naked MedMdrClassExtentRel.
// So, disable trimming.
fieldsUsed = Util.bitSetBetween(0, input.getRowType().getFieldCount());
}
return dispatchTrimFields(input, fieldsUsed, extraFields);
}
protected void explain_(RelNode rel, List<Pair<String, Object>> values) {
final Map<String, Object> map = jsonBuilder.map();
map.put("id", null); // ensure that id is the first attribute
map.put("relOp", relJson.classToTypeName(rel.getClass()));
for (Pair<String, Object> value : values) {
if (value.right instanceof RelNode) {
continue;
}
put(map, value.left, value.right);
}
// omit 'inputs: ["3"]' if "3" is the preceding rel
final List<Object> list = explainInputs(rel.getInputs());
if (list.size() != 1 || !list.get(0).equals(previousId)) {
map.put("inputs", list);
}
final String id = Integer.toString(relIdMap.size());
relIdMap.put(rel, id);
map.put("id", id);
relList.add(map);
previousId = id;
}
/** Variant of {@link #trimFields(RelNode, BitSet, Set)} for {@link AggregateRel}. */
public TrimResult trimFields(
AggregateRel aggregate, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) {
// Fields:
//
// | sys fields | group fields | agg functions |
//
// Two kinds of trimming:
//
// 1. If agg rel has system fields but none of these are used, create an
// agg rel with no system fields.
//
// 2. If aggregate functions are not used, remove them.
//
// But grouping fields stay, even if they are not used.
final RelDataType rowType = aggregate.getRowType();
// Compute which input fields are used.
BitSet inputFieldsUsed = new BitSet();
// 1. group fields are always used
for (int i : Util.toIter(aggregate.getGroupSet())) {
inputFieldsUsed.set(i);
}
// 2. agg functions
for (AggregateCall aggCall : aggregate.getAggCallList()) {
for (int i : aggCall.getArgList()) {
inputFieldsUsed.set(i);
}
}
// Create input with trimmed columns.
final RelNode input = aggregate.getInput(0);
final Set<RelDataTypeField> inputExtraFields = Collections.emptySet();
final TrimResult trimResult = trimChild(aggregate, input, inputFieldsUsed, inputExtraFields);
final RelNode newInput = trimResult.left;
final Mapping inputMapping = trimResult.right;
// If the input is unchanged, and we need to project all columns,
// there's nothing to do.
if (input == newInput && fieldsUsed.equals(Util.bitSetBetween(0, rowType.getFieldCount()))) {
return new TrimResult(aggregate, Mappings.createIdentity(rowType.getFieldCount()));
}
// Which agg calls are used by our consumer?
final int groupCount = aggregate.getGroupSet().cardinality();
int j = groupCount;
int usedAggCallCount = 0;
for (int i = 0; i < aggregate.getAggCallList().size(); i++) {
if (fieldsUsed.get(j++)) {
++usedAggCallCount;
}
}
// Offset due to the number of system fields having changed.
Mapping mapping =
Mappings.create(
MappingType.InverseSurjection, rowType.getFieldCount(), groupCount + usedAggCallCount);
final BitSet newGroupSet = Mappings.apply(inputMapping, aggregate.getGroupSet());
// Populate mapping of where to find the fields. System and grouping
// fields first.
for (IntPair pair : inputMapping) {
if (pair.source < groupCount) {
mapping.set(pair.source, pair.target);
}
}
// Now create new agg calls, and populate mapping for them.
final List<AggregateCall> newAggCallList = new ArrayList<AggregateCall>();
j = groupCount;
for (AggregateCall aggCall : aggregate.getAggCallList()) {
if (fieldsUsed.get(j)) {
AggregateCall newAggCall =
new AggregateCall(
aggCall.getAggregation(),
aggCall.isDistinct(),
Mappings.apply2(inputMapping, aggCall.getArgList()),
aggCall.getType(),
aggCall.getName());
if (newAggCall.equals(aggCall)) {
newAggCall = aggCall; // immutable -> canonize to save space
}
mapping.set(j, groupCount + newAggCallList.size());
newAggCallList.add(newAggCall);
}
++j;
}
RelNode newAggregate =
new AggregateRel(aggregate.getCluster(), newInput, newGroupSet, newAggCallList);
assert newAggregate.getClass() == aggregate.getClass();
return new TrimResult(newAggregate, 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);
}
