/**
* Creates a relational expression which projects an array of expressions, and optionally
* optimizes.
*
* <p>The result may not be a {@link ProjectRel}. If the projection is trivial, <code>child</code>
* is returned directly; and future versions may return other formulations of expressions, such as
* {@link CalcRel}.
*
* @param child input relational expression
* @param exprs list of expressions for the input columns
* @param fieldNames aliases of the expressions, or null to generate
* @param optimize Whether to return <code>child</code> unchanged if the projections are trivial.
*/
public static RelNode createProject(
RelNode child, List<RexNode> exprs, List<String> fieldNames, boolean optimize) {
final RelOptCluster cluster = child.getCluster();
final RexProgram program =
RexProgram.create(child.getRowType(), exprs, null, fieldNames, cluster.getRexBuilder());
final List<RelCollation> collationList = program.getCollations(child.getCollationList());
if (DeprecateProjectAndFilter) {
return new CalcRel(
cluster, child.getTraitSet(), child, program.getOutputRowType(), program, collationList);
} else {
final RelDataType rowType =
RexUtil.createStructType(cluster.getTypeFactory(), exprs, fieldNames);
if (optimize && RemoveTrivialProjectRule.isIdentity(exprs, rowType, child.getRowType())) {
return child;
}
return new ProjectRel(
cluster,
cluster.traitSetOf(
collationList.isEmpty() ? RelCollationImpl.EMPTY : collationList.get(0)),
child,
exprs,
rowType,
ProjectRelBase.Flags.Boxed);
}
}
/**
* Applies a mapping to a collation list.
*
* @param mapping Mapping
* @param collationList Collation list
* @return collation list with mapping applied to each field
*/
public static List<RelCollation> apply(
Mappings.TargetMapping mapping, List<RelCollation> collationList) {
final List<RelCollation> newCollationList = new ArrayList<RelCollation>();
for (RelCollation collation : collationList) {
final List<RelFieldCollation> newFieldCollationList = new ArrayList<RelFieldCollation>();
for (RelFieldCollation fieldCollation : collation.getFieldCollations()) {
final RelFieldCollation newFieldCollation = apply(mapping, fieldCollation);
if (newFieldCollation == null) {
// This field is not mapped. Stop here. The leading edge
// of the collation is still valid (although it's useless
// if it's empty).
break;
}
newFieldCollationList.add(newFieldCollation);
}
// Truncation to collations to their leading edge creates empty
// and duplicate collations. Ignore these.
if (!newFieldCollationList.isEmpty()) {
final RelCollationImpl newCollation = new RelCollationImpl(newFieldCollationList);
if (!newCollationList.contains(newCollation)) {
newCollationList.add(newCollation);
}
}
}
// REVIEW: There might be redundant collations in the list. For example,
// in {(x), (x, y)}, (x) is redundant because it is a leading edge of
// another collation in the list. Could remove redundant collations.
return newCollationList;
}
/**
* Creates a relational expression which projects an array of expressions, and optionally
* optimizes.
*
* <p>The result may not be a {@link ProjectRel}. If the projection is trivial, <code>child</code>
* is returned directly; and future versions may return other formulations of expressions, such as
* {@link CalcRel}.
*
* @param child input relational expression
* @param exprs list of expressions for the input columns
* @param fieldNames aliases of the expressions, or null to generate
* @param optimize Whether to return <code>child</code> unchanged if the projections are trivial.
*/
public static RelNode createProject(
RelNode child, List<RexNode> exprs, List<String> fieldNames, boolean optimize) {
final RelOptCluster cluster = child.getCluster();
final RexProgram program =
RexProgram.create(child.getRowType(), exprs, null, fieldNames, cluster.getRexBuilder());
final List<RelCollation> collationList = program.getCollations(child.getCollationList());
if (DEPRECATE_PROJECT_AND_FILTER) {
return new CalcRel(
cluster, child.getTraitSet(), child, program.getOutputRowType(), program, collationList);
} else {
final RelDataType rowType =
RexUtil.createStructType(
cluster.getTypeFactory(),
exprs,
fieldNames == null
? null
: SqlValidatorUtil.uniquify(fieldNames, SqlValidatorUtil.F_SUGGESTER));
if (optimize && RemoveTrivialProjectRule.isIdentity(exprs, rowType, child.getRowType())) {
return child;
}
return new ProjectRel(
cluster,
cluster.traitSetOf(
collationList.isEmpty() ? RelCollationImpl.EMPTY : collationList.get(0)),
child,
exprs,
rowType,
ProjectRelBase.Flags.BOXED);
}
}
/**
* Creates an OR expression from a list of RexNodes
*
* @param rexList list of RexNodes
* @return OR'd expression
*/
public static RexNode orRexNodeList(RexBuilder rexBuilder, List<RexNode> rexList) {
if (rexList.isEmpty()) {
return null;
}
RexNode orExpr = rexList.get(rexList.size() - 1);
for (int i = rexList.size() - 2; i >= 0; i--) {
orExpr = rexBuilder.makeCall(SqlStdOperatorTable.orOperator, rexList.get(i), orExpr);
}
return orExpr;
}
/**
* Creates an AND expression from a list of RexNodes
*
* @param rexList list of RexNodes
* @return AND'd expression
*/
public static RexNode andRexNodeList(RexBuilder rexBuilder, List<RexNode> rexList) {
if (rexList.isEmpty()) {
return null;
}
// create a right-deep tree to allow short-circuiting during
// expression evaluation
RexNode andExpr = rexList.get(rexList.size() - 1);
for (int i = rexList.size() - 2; i >= 0; i--) {
andExpr = rexBuilder.makeCall(SqlStdOperatorTable.andOperator, rexList.get(i), andExpr);
}
return andExpr;
}
/** 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);
}