/**
* Creates a relational expression which permutes the output fields of a relational expression
* according to a permutation.
*
* <p>Optimizations:
*
* <ul>
* <li>If the relational expression is a {@link CalcRel} or {@link ProjectRel} which is already
* acting as a permutation, combines the new permutation with the old;
* <li>If the permutation is the identity, returns the original relational expression.
* </ul>
*
* <p>If a permutation is combined with its inverse, these optimizations would combine to remove
* them both.
*
* @param rel Relational expression
* @param permutation Permutation to apply to fields
* @param fieldNames Field names; if null, or if a particular entry is null, the name of the
* permuted field is used
* @return relational expression which permutes its input fields
*/
public static RelNode permute(RelNode rel, Permutation permutation, List<String> fieldNames) {
if (permutation.isIdentity()) {
return rel;
}
if (rel instanceof CalcRel) {
CalcRel calcRel = (CalcRel) rel;
Permutation permutation1 = calcRel.getProgram().getPermutation();
if (permutation1 != null) {
Permutation permutation2 = permutation.product(permutation1);
return permute(rel, permutation2, null);
}
}
if (rel instanceof ProjectRel) {
Permutation permutation1 = ((ProjectRel) rel).getPermutation();
if (permutation1 != null) {
Permutation permutation2 = permutation.product(permutation1);
return permute(rel, permutation2, null);
}
}
final List<RelDataType> outputTypeList = new ArrayList<RelDataType>();
final List<String> outputNameList = new ArrayList<String>();
final List<RexNode> exprList = new ArrayList<RexNode>();
final List<RexLocalRef> projectRefList = new ArrayList<RexLocalRef>();
final List<RelDataTypeField> fields = rel.getRowType().getFieldList();
for (int i = 0; i < permutation.getTargetCount(); i++) {
int target = permutation.getTarget(i);
final RelDataTypeField targetField = fields.get(target);
outputTypeList.add(targetField.getType());
outputNameList.add(
((fieldNames == null) || (fieldNames.size() <= i) || (fieldNames.get(i) == null))
? targetField.getName()
: fieldNames.get(i));
exprList.add(rel.getCluster().getRexBuilder().makeInputRef(fields.get(i).getType(), i));
final int source = permutation.getSource(i);
projectRefList.add(new RexLocalRef(source, fields.get(source).getType()));
}
final RexProgram program =
new RexProgram(
rel.getRowType(),
exprList,
projectRefList,
null,
rel.getCluster().getTypeFactory().createStructType(outputTypeList, outputNameList));
return new CalcRel(
rel.getCluster(),
rel.getTraitSet(),
rel,
program.getOutputRowType(),
program,
Collections.<RelCollation>emptyList());
}
/**
* 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);
}
}
/**
* 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 a relational expression which filters according to a given condition, returning the
* same fields as its input.
*
* @param child Child relational expression
* @param condition Condition
* @return Relational expression
*/
public static RelNode createFilter(RelNode child, RexNode condition) {
if (DeprecateProjectAndFilter) {
final RelOptCluster cluster = child.getCluster();
RexProgramBuilder builder =
new RexProgramBuilder(child.getRowType(), cluster.getRexBuilder());
builder.addIdentity();
builder.addCondition(condition);
final RexProgram program = builder.getProgram();
return new CalcRel(
cluster,
child.getTraitSet(),
child,
program.getOutputRowType(),
program,
Collections.<RelCollation>emptyList());
} else {
return new FilterRel(child.getCluster(), child, condition);
}
}
/**
* Creates a relational expression which projects the output fields of a relational expression
* according to a partial mapping.
*
* <p>A partial mapping is weaker than a permutation: every target has one source, but a source
* may have 0, 1 or more than one targets. Usually the result will have fewer fields than the
* source, unless some source fields are projected multiple times.
*
* <p>This method could optimize the result as {@link #permute} does, but does not at present.
*
* @param rel Relational expression
* @param mapping Mapping from source fields to target fields. The mapping type must obey the
* constaints {@link MappingType#isMandatorySource()} and {@link
* MappingType#isSingleSource()}, as does {@link MappingType#InverseFunction}.
* @param fieldNames Field names; if null, or if a particular entry is null, the name of the
* permuted field is used
* @return relational expression which projects a subset of the input fields
*/
public static RelNode projectMapping(RelNode rel, Mapping mapping, List<String> fieldNames) {
assert mapping.getMappingType().isSingleSource();
assert mapping.getMappingType().isMandatorySource();
if (mapping.isIdentity()) {
return rel;
}
final List<RelDataType> outputTypeList = new ArrayList<RelDataType>();
final List<String> outputNameList = new ArrayList<String>();
final List<RexNode> exprList = new ArrayList<RexNode>();
final List<RexLocalRef> projectRefList = new ArrayList<RexLocalRef>();
final List<RelDataTypeField> fields = rel.getRowType().getFieldList();
for (int i = 0; i < fields.size(); i++) {
final RelDataTypeField field = fields.get(i);
exprList.add(rel.getCluster().getRexBuilder().makeInputRef(field.getType(), i));
}
for (int i = 0; i < mapping.getTargetCount(); i++) {
int source = mapping.getSource(i);
final RelDataTypeField sourceField = fields.get(source);
outputTypeList.add(sourceField.getType());
outputNameList.add(
((fieldNames == null) || (fieldNames.size() <= i) || (fieldNames.get(i) == null))
? sourceField.getName()
: fieldNames.get(i));
projectRefList.add(new RexLocalRef(source, sourceField.getType()));
}
final RexProgram program =
new RexProgram(
rel.getRowType(),
exprList,
projectRefList,
null,
rel.getCluster().getTypeFactory().createStructType(outputTypeList, outputNameList));
return new CalcRel(
rel.getCluster(),
rel.getTraitSet(),
rel,
program.getOutputRowType(),
program,
Collections.<RelCollation>emptyList());
}
/**
* 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()));
}
/**
* Creates new RelNodes replacing/removing the original project/row scan
*
* @param projectedScan new scan that is now projected
* @param origProject original projection
* @param needRename true if fields from the row scan need to be renamed
* @param newProject projection that contains the new projection expressions, in the case where
* the original projection cannot be removed because it projects expressions
* @return new RelNode
*/
public RelNode createNewRelNode(
RelNode projectedScan, ProjectRel origProject, boolean needRename, ProjectRel newProject) {
RelNode scanRel;
if (needRename) {
// Replace calling convention with FENNEL_EXEC_CONVENTION
RelTraitSet traits = RelOptUtil.clone(origProject.getTraits());
traits.setTrait(CallingConventionTraitDef.instance, FennelRel.FENNEL_EXEC_CONVENTION);
if (!traits.equals(projectedScan.getTraits())) {
RelNode mergedProjectedScan = convert(projectedScan, traits);
RelOptPlanner planner = projectedScan.getCluster().getPlanner();
// register projectedScan == mergedProjectedScan
// so mergedProjectedScan will have a set later on
projectedScan = planner.ensureRegistered(mergedProjectedScan, projectedScan);
}
scanRel =
new FennelRenameRel(
origProject.getCluster(),
projectedScan,
RelOptUtil.getFieldNames(origProject.getRowType()),
traits);
} else {
scanRel = projectedScan;
}
if (newProject == null) {
return scanRel;
} else {
// in the case where the projection had expressions, put the
// new, modified projection on top of the projected row scan
return (ProjectRel)
CalcRel.createProject(
scanRel,
newProject.getProjectExps(),
RelOptUtil.getFieldNames(newProject.getRowType()));
}
}
static FarragoSession getSession(RelNode rel) {
FarragoSessionPlanner planner = (FarragoSessionPlanner) rel.getCluster().getPlanner();
FarragoSessionPreparingStmt preparingStmt = planner.getPreparingStmt();
return preparingStmt.getSession();
}
/**
* Reduces a list of expressions.
*
* @param rel Relational expression
* @param expList List of expressions, modified in place
* @return whether reduction found something to change, and succeeded
*/
static boolean reduceExpressions(RelNode rel, List<RexNode> expList) {
RexBuilder rexBuilder = rel.getCluster().getRexBuilder();
// Find reducible expressions.
FarragoSessionPlanner planner = (FarragoSessionPlanner) rel.getCluster().getPlanner();
FarragoSessionPreparingStmt preparingStmt = planner.getPreparingStmt();
List<RexNode> constExps = new ArrayList<RexNode>();
List<Boolean> addCasts = new ArrayList<Boolean>();
List<RexNode> removableCasts = new ArrayList<RexNode>();
findReducibleExps(preparingStmt, expList, constExps, addCasts, removableCasts);
if (constExps.isEmpty() && removableCasts.isEmpty()) {
return false;
}
// Remove redundant casts before reducing constant expressions.
// If the argument to the redundant cast is a reducible constant,
// reducing that argument to a constant first will result in not being
// able to locate the original cast expression.
if (!removableCasts.isEmpty()) {
List<RexNode> reducedExprs = new ArrayList<RexNode>();
List<Boolean> noCasts = new ArrayList<Boolean>();
for (RexNode exp : removableCasts) {
RexCall call = (RexCall) exp;
reducedExprs.add(call.getOperands()[0]);
noCasts.add(false);
}
RexReplacer replacer = new RexReplacer(rexBuilder, removableCasts, reducedExprs, noCasts);
replacer.apply(expList);
}
if (constExps.isEmpty()) {
return true;
}
// Compute the values they reduce to.
List<RexNode> reducedValues = new ArrayList<RexNode>();
ReentrantValuesStmt reentrantStmt =
new ReentrantValuesStmt(
preparingStmt.getRootStmtContext(), rexBuilder, constExps, reducedValues);
FarragoSession session = getSession(rel);
reentrantStmt.execute(session, true);
if (reentrantStmt.failed) {
return false;
}
// For ProjectRel, we have to be sure to preserve the result
// types, so always cast regardless of the expression type.
// For other RelNodes like FilterRel, in general, this isn't necessary,
// and the presence of casts could hinder other rules such as sarg
// analysis, which require bare literals. But there are special cases,
// like when the expression is a UDR argument, that need to be
// handled as special cases.
if (rel instanceof ProjectRel) {
for (int i = 0; i < reducedValues.size(); i++) {
addCasts.set(i, true);
}
}
RexReplacer replacer = new RexReplacer(rexBuilder, constExps, reducedValues, addCasts);
replacer.apply(expList);
return true;
}