Examples with ScanCollectionUnnestingFunctionFactory org.apache.asterix.runtime.unnestingfunctions.std.ScanCollectionDescriptor.ScanCollectionUnnestingFunctionFactory used on opensource projects

Example 1 with ScanCollectionUnnestingFunctionFactory

use of org.apache.asterix.runtime.unnestingfunctions.std.ScanCollectionDescriptor.ScanCollectionUnnestingFunctionFactory in project asterixdb by apache.

the class AbstractScalarAggregateDescriptor method createEvaluatorFactory.

@Override
public IScalarEvaluatorFactory createEvaluatorFactory(final IScalarEvaluatorFactory[] args) throws AlgebricksException {
    // The aggregate function will get a SingleFieldFrameTupleReference that points to the result of the ScanCollection.
    // The list-item will always reside in the first field (column) of the SingleFieldFrameTupleReference.
    IScalarEvaluatorFactory[] aggFuncArgs = new IScalarEvaluatorFactory[1];
    aggFuncArgs[0] = new ColumnAccessEvalFactory(0);
    // Create aggregate function from this scalar version.
    FunctionIdentifier fid = BuiltinFunctions.getAggregateFunction(getIdentifier());
    IFunctionManager mgr = FunctionManagerHolder.getFunctionManager();
    IFunctionDescriptor fd = mgr.lookupFunction(fid);
    AbstractAggregateFunctionDynamicDescriptor aggFuncDesc = (AbstractAggregateFunctionDynamicDescriptor) fd;
    final IAggregateEvaluatorFactory aggFuncFactory = aggFuncDesc.createAggregateEvaluatorFactory(aggFuncArgs);
    return new IScalarEvaluatorFactory() {

        private static final long serialVersionUID = 1L;

        @Override
        public IScalarEvaluator createScalarEvaluator(IHyracksTaskContext ctx) throws HyracksDataException {
            // Use ScanCollection to iterate over list items.
            ScanCollectionUnnestingFunctionFactory scanCollectionFactory = new ScanCollectionUnnestingFunctionFactory(args[0]);
            return new GenericScalarAggregateFunction(aggFuncFactory.createAggregateEvaluator(ctx), scanCollectionFactory, ctx);
        }
    };
}