presto-main/src/main/java/io/prestosql/operator/unnest/UnnestOperator.java/UnnestOperator/prepareForNewOutput
class UnnestOperator:    private void prepareForNewOutput(PageBuilderStatus pageBuilderStatus)
    {
        unnesters.forEach(unnester -> unnester.startNewOutput(pageBuilderStatus, estimatedMaxRowsPerBlock));
        replicatedBlockBuilders.forEach(replicatedBlockBuilder -> replicatedBlockBuilder.startNewOutput(estimatedMaxRowsPerBlock));

        if (withOrdinality) {
            ordinalityBlockBuilder = BIGINT.createBlockBuilder(pageBuilderStatus.createBlockBuilderStatus(), estimatedMaxRowsPerBlock);
        }
    }