Examples with RexSimplify org.apache.calcite.rex.RexSimplify used on opensource projects

Example 1 with RexSimplify

use of org.apache.calcite.rex.RexSimplify in project calcite by apache.

the class RelMdPredicates method getPredicates.

/**
 * Infers predicates for a Union.
 */
public RelOptPredicateList getPredicates(Union union, RelMetadataQuery mq) {
    RexBuilder rexBuilder = union.getCluster().getRexBuilder();
    Map<String, RexNode> finalPreds = new HashMap<>();
    List<RexNode> finalResidualPreds = new ArrayList<>();
    for (int i = 0; i < union.getInputs().size(); i++) {
        RelNode input = union.getInputs().get(i);
        RelOptPredicateList info = mq.getPulledUpPredicates(input);
        if (info.pulledUpPredicates.isEmpty()) {
            return RelOptPredicateList.EMPTY;
        }
        Map<String, RexNode> preds = new HashMap<>();
        List<RexNode> residualPreds = new ArrayList<>();
        for (RexNode pred : info.pulledUpPredicates) {
            final String predDigest = pred.toString();
            if (i == 0) {
                preds.put(predDigest, pred);
                continue;
            }
            if (finalPreds.containsKey(predDigest)) {
                preds.put(predDigest, pred);
            } else {
                residualPreds.add(pred);
            }
        }
        // Add new residual preds
        finalResidualPreds.add(RexUtil.composeConjunction(rexBuilder, residualPreds, false));
        // Add those that are not part of the final set to residual
        for (Entry<String, RexNode> e : finalPreds.entrySet()) {
            if (!preds.containsKey(e.getKey())) {
                // This node was in previous union inputs, but it is not in this one
                for (int j = 0; j < i; j++) {
                    finalResidualPreds.set(j, RexUtil.composeConjunction(rexBuilder, Lists.newArrayList(finalResidualPreds.get(j), e.getValue()), false));
                }
            }
        }
        // Final preds
        finalPreds = preds;
    }
    List<RexNode> preds = new ArrayList<>(finalPreds.values());
    final RelOptCluster cluster = union.getCluster();
    final RexExecutor executor = Util.first(cluster.getPlanner().getExecutor(), RexUtil.EXECUTOR);
    final RelOptPredicateList predicates = RelOptPredicateList.EMPTY;
    final RexSimplify simplify = new RexSimplify(rexBuilder, predicates, true, executor);
    RexNode disjPred = simplify.simplifyOrs(finalResidualPreds);
    if (!disjPred.isAlwaysTrue()) {
        preds.add(disjPred);
    }
    return RelOptPredicateList.of(rexBuilder, preds);
}

Example 2 with RexSimplify

use of org.apache.calcite.rex.RexSimplify in project calcite by apache.

the class RelMdPredicates method getPredicates.

/**
 * Infers predicates for a {@link org.apache.calcite.rel.core.Join} (including
 * {@link org.apache.calcite.rel.core.SemiJoin}).
 */
public RelOptPredicateList getPredicates(Join join, RelMetadataQuery mq) {
    RelOptCluster cluster = join.getCluster();
    RexBuilder rexBuilder = cluster.getRexBuilder();
    final RexExecutor executor = Util.first(cluster.getPlanner().getExecutor(), RexUtil.EXECUTOR);
    final RelNode left = join.getInput(0);
    final RelNode right = join.getInput(1);
    final RelOptPredicateList leftInfo = mq.getPulledUpPredicates(left);
    final RelOptPredicateList rightInfo = mq.getPulledUpPredicates(right);
    final RexSimplify simplifier = new RexSimplify(rexBuilder, RelOptPredicateList.EMPTY, true, executor);
    JoinConditionBasedPredicateInference joinInference = new JoinConditionBasedPredicateInference(join, RexUtil.composeConjunction(rexBuilder, leftInfo.pulledUpPredicates, false), RexUtil.composeConjunction(rexBuilder, rightInfo.pulledUpPredicates, false), simplifier);
    return joinInference.inferPredicates(false);
}

Example 3 with RexSimplify

use of org.apache.calcite.rex.RexSimplify in project calcite by apache.

the class EnumerableCalc method implement.

public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
    final JavaTypeFactory typeFactory = implementor.getTypeFactory();
    final BlockBuilder builder = new BlockBuilder();
    final EnumerableRel child = (EnumerableRel) getInput();
    final Result result = implementor.visitChild(this, 0, child, pref);
    final PhysType physType = PhysTypeImpl.of(typeFactory, getRowType(), pref.prefer(result.format));
    // final Enumerable<Employee> inputEnumerable = <<child adapter>>;
    // return new Enumerable<IntString>() {
    // Enumerator<IntString> enumerator() {
    // return new Enumerator<IntString>() {
    // public void reset() {
    // ...
    Type outputJavaType = physType.getJavaRowType();
    final Type enumeratorType = Types.of(Enumerator.class, outputJavaType);
    Type inputJavaType = result.physType.getJavaRowType();
    ParameterExpression inputEnumerator = Expressions.parameter(Types.of(Enumerator.class, inputJavaType), "inputEnumerator");
    Expression input = RexToLixTranslator.convert(Expressions.call(inputEnumerator, BuiltInMethod.ENUMERATOR_CURRENT.method), inputJavaType);
    final RexBuilder rexBuilder = getCluster().getRexBuilder();
    final RelMetadataQuery mq = RelMetadataQuery.instance();
    final RelOptPredicateList predicates = mq.getPulledUpPredicates(child);
    final RexSimplify simplify = new RexSimplify(rexBuilder, predicates, false, RexUtil.EXECUTOR);
    final RexProgram program = this.program.normalize(rexBuilder, simplify);
    BlockStatement moveNextBody;
    if (program.getCondition() == null) {
        moveNextBody = Blocks.toFunctionBlock(Expressions.call(inputEnumerator, BuiltInMethod.ENUMERATOR_MOVE_NEXT.method));
    } else {
        final BlockBuilder builder2 = new BlockBuilder();
        Expression condition = RexToLixTranslator.translateCondition(program, typeFactory, builder2, new RexToLixTranslator.InputGetterImpl(Collections.singletonList(Pair.of(input, result.physType))), implementor.allCorrelateVariables);
        builder2.add(Expressions.ifThen(condition, Expressions.return_(null, Expressions.constant(true))));
        moveNextBody = Expressions.block(Expressions.while_(Expressions.call(inputEnumerator, BuiltInMethod.ENUMERATOR_MOVE_NEXT.method), builder2.toBlock()), Expressions.return_(null, Expressions.constant(false)));
    }
    final BlockBuilder builder3 = new BlockBuilder();
    List<Expression> expressions = RexToLixTranslator.translateProjects(program, typeFactory, builder3, physType, DataContext.ROOT, new RexToLixTranslator.InputGetterImpl(Collections.singletonList(Pair.of(input, result.physType))), implementor.allCorrelateVariables);
    builder3.add(Expressions.return_(null, physType.record(expressions)));
    BlockStatement currentBody = builder3.toBlock();
    final Expression inputEnumerable = builder.append("inputEnumerable", result.block, false);
    final Expression body = Expressions.new_(enumeratorType, NO_EXPRS, Expressions.list(Expressions.fieldDecl(Modifier.PUBLIC | Modifier.FINAL, inputEnumerator, Expressions.call(inputEnumerable, BuiltInMethod.ENUMERABLE_ENUMERATOR.method)), EnumUtils.overridingMethodDecl(BuiltInMethod.ENUMERATOR_RESET.method, NO_PARAMS, Blocks.toFunctionBlock(Expressions.call(inputEnumerator, BuiltInMethod.ENUMERATOR_RESET.method))), EnumUtils.overridingMethodDecl(BuiltInMethod.ENUMERATOR_MOVE_NEXT.method, NO_PARAMS, moveNextBody), EnumUtils.overridingMethodDecl(BuiltInMethod.ENUMERATOR_CLOSE.method, NO_PARAMS, Blocks.toFunctionBlock(Expressions.call(inputEnumerator, BuiltInMethod.ENUMERATOR_CLOSE.method))), Expressions.methodDecl(Modifier.PUBLIC, BRIDGE_METHODS ? Object.class : outputJavaType, "current", NO_PARAMS, currentBody)));
    builder.add(Expressions.return_(null, Expressions.new_(BuiltInMethod.ABSTRACT_ENUMERABLE_CTOR.constructor, // Collections.singletonList(inputRowType),
    NO_EXPRS, ImmutableList.<MemberDeclaration>of(Expressions.methodDecl(Modifier.PUBLIC, enumeratorType, BuiltInMethod.ENUMERABLE_ENUMERATOR.method.getName(), NO_PARAMS, Blocks.toFunctionBlock(body))))));
    return implementor.result(physType, builder.toBlock());
}

Example 4 with RexSimplify

use of org.apache.calcite.rex.RexSimplify in project calcite by apache.

the class AbstractMaterializedViewRule method perform.

/**
 * Rewriting logic is based on "Optimizing Queries Using Materialized Views:
 * A Practical, Scalable Solution" by Goldstein and Larson.
 *
 * <p>On the query side, rules matches a Project-node chain or node, where node
 * is either an Aggregate or a Join. Subplan rooted at the node operator must
 * be composed of one or more of the following operators: TableScan, Project,
 * Filter, and Join.
 *
 * <p>For each join MV, we need to check the following:
 * <ol>
 * <li> The plan rooted at the Join operator in the view produces all rows
 * needed by the plan rooted at the Join operator in the query.</li>
 * <li> All columns required by compensating predicates, i.e., predicates that
 * need to be enforced over the view, are available at the view output.</li>
 * <li> All output expressions can be computed from the output of the view.</li>
 * <li> All output rows occur with the correct duplication factor. We might
 * rely on existing Unique-Key - Foreign-Key relationships to extract that
 * information.</li>
 * </ol>
 *
 * <p>In turn, for each aggregate MV, we need to check the following:
 * <ol>
 * <li> The plan rooted at the Aggregate operator in the view produces all rows
 * needed by the plan rooted at the Aggregate operator in the query.</li>
 * <li> All columns required by compensating predicates, i.e., predicates that
 * need to be enforced over the view, are available at the view output.</li>
 * <li> The grouping columns in the query are a subset of the grouping columns
 * in the view.</li>
 * <li> All columns required to perform further grouping are available in the
 * view output.</li>
 * <li> All columns required to compute output expressions are available in the
 * view output.</li>
 * </ol>
 *
 * <p>The rule contains multiple extensions compared to the original paper. One of
 * them is the possibility of creating rewritings using Union operators, e.g., if
 * the result of a query is partially contained in the materialized view.
 */
protected void perform(RelOptRuleCall call, Project topProject, RelNode node) {
    final RexBuilder rexBuilder = node.getCluster().getRexBuilder();
    final RelMetadataQuery mq = RelMetadataQuery.instance();
    final RelOptPlanner planner = call.getPlanner();
    final RexExecutor executor = Util.first(planner.getExecutor(), RexUtil.EXECUTOR);
    final RelOptPredicateList predicates = RelOptPredicateList.EMPTY;
    final RexSimplify simplify = new RexSimplify(rexBuilder, predicates, true, executor);
    final List<RelOptMaterialization> materializations = (planner instanceof VolcanoPlanner) ? ((VolcanoPlanner) planner).getMaterializations() : ImmutableList.<RelOptMaterialization>of();
    if (!materializations.isEmpty()) {
        // try to generate a rewriting are met
        if (!isValidPlan(topProject, node, mq)) {
            return;
        }
        // Obtain applicable (filtered) materializations
        // TODO: Filtering of relevant materializations needs to be
        // improved so we gather only materializations that might
        // actually generate a valid rewriting.
        final List<RelOptMaterialization> applicableMaterializations = RelOptMaterializations.getApplicableMaterializations(node, materializations);
        if (!applicableMaterializations.isEmpty()) {
            // 2. Initialize all query related auxiliary data structures
            // that will be used throughout query rewriting process
            // Generate query table references
            final Set<RelTableRef> queryTableRefs = mq.getTableReferences(node);
            if (queryTableRefs == null) {
                // Bail out
                return;
            }
            // Extract query predicates
            final RelOptPredicateList queryPredicateList = mq.getAllPredicates(node);
            if (queryPredicateList == null) {
                // Bail out
                return;
            }
            final RexNode pred = simplify.simplify(RexUtil.composeConjunction(rexBuilder, queryPredicateList.pulledUpPredicates, false));
            final Triple<RexNode, RexNode, RexNode> queryPreds = splitPredicates(rexBuilder, pred);
            // Extract query equivalence classes. An equivalence class is a set
            // of columns in the query output that are known to be equal.
            final EquivalenceClasses qEC = new EquivalenceClasses();
            for (RexNode conj : RelOptUtil.conjunctions(queryPreds.getLeft())) {
                assert conj.isA(SqlKind.EQUALS);
                RexCall equiCond = (RexCall) conj;
                qEC.addEquivalenceClass((RexTableInputRef) equiCond.getOperands().get(0), (RexTableInputRef) equiCond.getOperands().get(1));
            }
            // rewrite the given query
            for (RelOptMaterialization materialization : applicableMaterializations) {
                RelNode view = materialization.tableRel;
                Project topViewProject;
                RelNode viewNode;
                if (materialization.queryRel instanceof Project) {
                    topViewProject = (Project) materialization.queryRel;
                    viewNode = topViewProject.getInput();
                } else {
                    topViewProject = null;
                    viewNode = materialization.queryRel;
                }
                // 3.1. View checks before proceeding
                if (!isValidPlan(topViewProject, viewNode, mq)) {
                    // Skip it
                    continue;
                }
                // 3.2. Initialize all query related auxiliary data structures
                // that will be used throughout query rewriting process
                // Extract view predicates
                final RelOptPredicateList viewPredicateList = mq.getAllPredicates(viewNode);
                if (viewPredicateList == null) {
                    // Skip it
                    continue;
                }
                final RexNode viewPred = simplify.simplify(RexUtil.composeConjunction(rexBuilder, viewPredicateList.pulledUpPredicates, false));
                final Triple<RexNode, RexNode, RexNode> viewPreds = splitPredicates(rexBuilder, viewPred);
                // Extract view table references
                final Set<RelTableRef> viewTableRefs = mq.getTableReferences(viewNode);
                if (viewTableRefs == null) {
                    // Bail out
                    return;
                }
                // Extract view tables
                MatchModality matchModality;
                Multimap<RexTableInputRef, RexTableInputRef> compensationEquiColumns = ArrayListMultimap.create();
                if (!queryTableRefs.equals(viewTableRefs)) {
                    // subset of query tables (add additional tables through joins if possible)
                    if (viewTableRefs.containsAll(queryTableRefs)) {
                        matchModality = MatchModality.QUERY_PARTIAL;
                        final EquivalenceClasses vEC = new EquivalenceClasses();
                        for (RexNode conj : RelOptUtil.conjunctions(viewPreds.getLeft())) {
                            assert conj.isA(SqlKind.EQUALS);
                            RexCall equiCond = (RexCall) conj;
                            vEC.addEquivalenceClass((RexTableInputRef) equiCond.getOperands().get(0), (RexTableInputRef) equiCond.getOperands().get(1));
                        }
                        if (!compensatePartial(viewTableRefs, vEC, queryTableRefs, compensationEquiColumns)) {
                            // Cannot rewrite, skip it
                            continue;
                        }
                    } else if (queryTableRefs.containsAll(viewTableRefs)) {
                        matchModality = MatchModality.VIEW_PARTIAL;
                        ViewPartialRewriting partialRewritingResult = compensateViewPartial(call.builder(), rexBuilder, mq, view, topProject, node, queryTableRefs, qEC, topViewProject, viewNode, viewTableRefs);
                        if (partialRewritingResult == null) {
                            // Cannot rewrite, skip it
                            continue;
                        }
                        // Rewrite succeeded
                        view = partialRewritingResult.newView;
                        topViewProject = partialRewritingResult.newTopViewProject;
                        viewNode = partialRewritingResult.newViewNode;
                    } else {
                        // Skip it
                        continue;
                    }
                } else {
                    matchModality = MatchModality.COMPLETE;
                }
                // 4. We map every table in the query to a table with the same qualified
                // name (all query tables are contained in the view, thus this is equivalent
                // to mapping every table in the query to a view table).
                final Multimap<RelTableRef, RelTableRef> multiMapTables = ArrayListMultimap.create();
                for (RelTableRef queryTableRef1 : queryTableRefs) {
                    for (RelTableRef queryTableRef2 : queryTableRefs) {
                        if (queryTableRef1.getQualifiedName().equals(queryTableRef2.getQualifiedName())) {
                            multiMapTables.put(queryTableRef1, queryTableRef2);
                        }
                    }
                }
                // If a table is used multiple times, we will create multiple mappings,
                // and we will try to rewrite the query using each of the mappings.
                // Then, we will try to map every source table (query) to a target
                // table (view), and if we are successful, we will try to create
                // compensation predicates to filter the view results further
                // (if needed).
                final List<BiMap<RelTableRef, RelTableRef>> flatListMappings = generateTableMappings(multiMapTables);
                for (BiMap<RelTableRef, RelTableRef> queryToViewTableMapping : flatListMappings) {
                    // TableMapping : mapping query tables -> view tables
                    // 4.0. If compensation equivalence classes exist, we need to add
                    // the mapping to the query mapping
                    final EquivalenceClasses currQEC = EquivalenceClasses.copy(qEC);
                    if (matchModality == MatchModality.QUERY_PARTIAL) {
                        for (Entry<RexTableInputRef, RexTableInputRef> e : compensationEquiColumns.entries()) {
                            // Copy origin
                            RelTableRef queryTableRef = queryToViewTableMapping.inverse().get(e.getKey().getTableRef());
                            RexTableInputRef queryColumnRef = RexTableInputRef.of(queryTableRef, e.getKey().getIndex(), e.getKey().getType());
                            // Add to query equivalence classes and table mapping
                            currQEC.addEquivalenceClass(queryColumnRef, e.getValue());
                            queryToViewTableMapping.put(e.getValue().getTableRef(), // identity
                            e.getValue().getTableRef());
                        }
                    }
                    // 4.1. Compute compensation predicates, i.e., predicates that need to be
                    // enforced over the view to retain query semantics. The resulting predicates
                    // are expressed using {@link RexTableInputRef} over the query.
                    // First, to establish relationship, we swap column references of the view
                    // predicates to point to query tables and compute equivalence classes.
                    final RexNode viewColumnsEquiPred = RexUtil.swapTableReferences(rexBuilder, viewPreds.getLeft(), queryToViewTableMapping.inverse());
                    final EquivalenceClasses queryBasedVEC = new EquivalenceClasses();
                    for (RexNode conj : RelOptUtil.conjunctions(viewColumnsEquiPred)) {
                        assert conj.isA(SqlKind.EQUALS);
                        RexCall equiCond = (RexCall) conj;
                        queryBasedVEC.addEquivalenceClass((RexTableInputRef) equiCond.getOperands().get(0), (RexTableInputRef) equiCond.getOperands().get(1));
                    }
                    Triple<RexNode, RexNode, RexNode> compensationPreds = computeCompensationPredicates(rexBuilder, simplify, currQEC, queryPreds, queryBasedVEC, viewPreds, queryToViewTableMapping);
                    if (compensationPreds == null && generateUnionRewriting) {
                        // Attempt partial rewriting using union operator. This rewriting
                        // will read some data from the view and the rest of the data from
                        // the query computation. The resulting predicates are expressed
                        // using {@link RexTableInputRef} over the view.
                        compensationPreds = computeCompensationPredicates(rexBuilder, simplify, queryBasedVEC, viewPreds, currQEC, queryPreds, queryToViewTableMapping.inverse());
                        if (compensationPreds == null) {
                            // This was our last chance to use the view, skip it
                            continue;
                        }
                        RexNode compensationColumnsEquiPred = compensationPreds.getLeft();
                        RexNode otherCompensationPred = RexUtil.composeConjunction(rexBuilder, ImmutableList.of(compensationPreds.getMiddle(), compensationPreds.getRight()), false);
                        assert !compensationColumnsEquiPred.isAlwaysTrue() || !otherCompensationPred.isAlwaysTrue();
                        // b. Generate union branch (query).
                        final RelNode unionInputQuery = rewriteQuery(call.builder(), rexBuilder, simplify, mq, compensationColumnsEquiPred, otherCompensationPred, topProject, node, queryToViewTableMapping, queryBasedVEC, currQEC);
                        if (unionInputQuery == null) {
                            // Skip it
                            continue;
                        }
                        // c. Generate union branch (view).
                        // We trigger the unifying method. This method will either create a Project
                        // or an Aggregate operator on top of the view. It will also compute the
                        // output expressions for the query.
                        final RelNode unionInputView = rewriteView(call.builder(), rexBuilder, simplify, mq, matchModality, true, view, topProject, node, topViewProject, viewNode, queryToViewTableMapping, currQEC);
                        if (unionInputView == null) {
                            // Skip it
                            continue;
                        }
                        // d. Generate final rewriting (union).
                        final RelNode result = createUnion(call.builder(), rexBuilder, topProject, unionInputQuery, unionInputView);
                        if (result == null) {
                            // Skip it
                            continue;
                        }
                        call.transformTo(result);
                    } else if (compensationPreds != null) {
                        RexNode compensationColumnsEquiPred = compensationPreds.getLeft();
                        RexNode otherCompensationPred = RexUtil.composeConjunction(rexBuilder, ImmutableList.of(compensationPreds.getMiddle(), compensationPreds.getRight()), false);
                        // a. Compute final compensation predicate.
                        if (!compensationColumnsEquiPred.isAlwaysTrue() || !otherCompensationPred.isAlwaysTrue()) {
                            // All columns required by compensating predicates must be contained
                            // in the view output (condition 2).
                            List<RexNode> viewExprs = topViewProject == null ? extractReferences(rexBuilder, view) : topViewProject.getChildExps();
                            // since we want to enforce the rest
                            if (!compensationColumnsEquiPred.isAlwaysTrue()) {
                                compensationColumnsEquiPred = rewriteExpression(rexBuilder, mq, view, viewNode, viewExprs, queryToViewTableMapping.inverse(), queryBasedVEC, false, compensationColumnsEquiPred);
                                if (compensationColumnsEquiPred == null) {
                                    // Skip it
                                    continue;
                                }
                            }
                            // For the rest, we use the query equivalence classes
                            if (!otherCompensationPred.isAlwaysTrue()) {
                                otherCompensationPred = rewriteExpression(rexBuilder, mq, view, viewNode, viewExprs, queryToViewTableMapping.inverse(), currQEC, true, otherCompensationPred);
                                if (otherCompensationPred == null) {
                                    // Skip it
                                    continue;
                                }
                            }
                        }
                        final RexNode viewCompensationPred = RexUtil.composeConjunction(rexBuilder, ImmutableList.of(compensationColumnsEquiPred, otherCompensationPred), false);
                        // b. Generate final rewriting if possible.
                        // First, we add the compensation predicate (if any) on top of the view.
                        // Then, we trigger the unifying method. This method will either create a
                        // Project or an Aggregate operator on top of the view. It will also compute
                        // the output expressions for the query.
                        RelBuilder builder = call.builder();
                        RelNode viewWithFilter;
                        if (!viewCompensationPred.isAlwaysTrue()) {
                            RexNode newPred = simplify.simplify(viewCompensationPred);
                            viewWithFilter = builder.push(view).filter(newPred).build();
                            // We add (and push) the filter to the view plan before triggering the rewriting.
                            // This is useful in case some of the columns can be folded to same value after
                            // filter is added.
                            Pair<RelNode, RelNode> pushedNodes = pushFilterToOriginalViewPlan(builder, topViewProject, viewNode, newPred);
                            topViewProject = (Project) pushedNodes.left;
                            viewNode = pushedNodes.right;
                        } else {
                            viewWithFilter = builder.push(view).build();
                        }
                        final RelNode result = rewriteView(builder, rexBuilder, simplify, mq, matchModality, false, viewWithFilter, topProject, node, topViewProject, viewNode, queryToViewTableMapping, currQEC);
                        if (result == null) {
                            // Skip it
                            continue;
                        }
                        call.transformTo(result);
                    }
                // end else
                }
            }
        }
    }
}

Example 5 with RexSimplify

use of org.apache.calcite.rex.RexSimplify in project calcite by apache.

the class RexProgramTest method setUp.

@Before
public void setUp() {
    typeFactory = new JavaTypeFactoryImpl(RelDataTypeSystem.DEFAULT);
    rexBuilder = new RexBuilder(typeFactory);
    RexExecutor executor = new RexExecutorImpl(new DummyTestDataContext());
    simplify = new RexSimplify(rexBuilder, RelOptPredicateList.EMPTY, false, executor);
    trueLiteral = rexBuilder.makeLiteral(true);
    falseLiteral = rexBuilder.makeLiteral(false);
    final RelDataType intType = typeFactory.createSqlType(SqlTypeName.INTEGER);
    nullLiteral = rexBuilder.makeNullLiteral(intType);
    unknownLiteral = rexBuilder.makeNullLiteral(trueLiteral.getType());
}