Examples with StreamLimitPOperator org.apache.hyracks.algebricks.core.algebra.operators.physical.StreamLimitPOperator used on opensource projects

Example 1 with StreamLimitPOperator

use of org.apache.hyracks.algebricks.core.algebra.operators.physical.StreamLimitPOperator in project asterixdb by apache.

the class CopyLimitDownRule method rewritePre.

@Override
public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
    AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
    if (op.getOperatorTag() != LogicalOperatorTag.LIMIT) {
        return false;
    }
    LimitOperator limitOp = (LimitOperator) op;
    if (!limitOp.isTopmostLimitOp()) {
        return false;
    }
    List<LogicalVariable> limitUsedVars = new ArrayList<>();
    VariableUtilities.getUsedVariables(limitOp, limitUsedVars);
    Mutable<ILogicalOperator> safeOpRef = null;
    Mutable<ILogicalOperator> candidateOpRef = limitOp.getInputs().get(0);
    List<LogicalVariable> candidateProducedVars = new ArrayList<>();
    while (true) {
        candidateProducedVars.clear();
        ILogicalOperator candidateOp = candidateOpRef.getValue();
        LogicalOperatorTag candidateOpTag = candidateOp.getOperatorTag();
        if (candidateOp.getInputs().size() > 1 || !candidateOp.isMap() || candidateOpTag == LogicalOperatorTag.SELECT || candidateOpTag == LogicalOperatorTag.LIMIT || candidateOpTag == LogicalOperatorTag.UNNEST_MAP || !OperatorPropertiesUtil.disjoint(limitUsedVars, candidateProducedVars)) {
            break;
        }
        safeOpRef = candidateOpRef;
        candidateOpRef = safeOpRef.getValue().getInputs().get(0);
    }
    if (safeOpRef != null) {
        ILogicalOperator safeOp = safeOpRef.getValue();
        Mutable<ILogicalOperator> unsafeOpRef = safeOp.getInputs().get(0);
        ILogicalOperator unsafeOp = unsafeOpRef.getValue();
        LimitOperator limitCloneOp = null;
        if (limitOp.getOffset().getValue() == null) {
            limitCloneOp = new LimitOperator(limitOp.getMaxObjects().getValue(), false);
        } else {
            // Need to add an offset to the given limit value
            // since the original topmost limit will use the offset value.
            // We can't apply the offset multiple times.
            IFunctionInfo finfoAdd = context.getMetadataProvider().lookupFunction(AlgebricksBuiltinFunctions.NUMERIC_ADD);
            List<Mutable<ILogicalExpression>> addArgs = new ArrayList<>();
            addArgs.add(new MutableObject<ILogicalExpression>(limitOp.getMaxObjects().getValue().cloneExpression()));
            addArgs.add(new MutableObject<ILogicalExpression>(limitOp.getOffset().getValue().cloneExpression()));
            ScalarFunctionCallExpression maxPlusOffset = new ScalarFunctionCallExpression(finfoAdd, addArgs);
            limitCloneOp = new LimitOperator(maxPlusOffset, false);
        }
        limitCloneOp.setPhysicalOperator(new StreamLimitPOperator());
        limitCloneOp.getInputs().add(new MutableObject<ILogicalOperator>(unsafeOp));
        limitCloneOp.setExecutionMode(unsafeOp.getExecutionMode());
        OperatorPropertiesUtil.computeSchemaRecIfNull((AbstractLogicalOperator) unsafeOp);
        limitCloneOp.recomputeSchema();
        unsafeOpRef.setValue(limitCloneOp);
        context.computeAndSetTypeEnvironmentForOperator(limitCloneOp);
        context.addToDontApplySet(this, limitOp);
    }
    return safeOpRef != null;
}