I created a partitioning logic on my code to parse a file into more files and download one partition of all of them, i merged it into the api, it dont partitioning i have readed all my code and i dont see the problem, i dont know if its on the download call or on the select file code

i want some help, i will provide some of my code

public Single<FileResponse> Descarga(int pageSize, String sortField, String sortOrder) {

    return Single.defer(() -> {

        final var fileName = LocalDate.now ()+compress (sortField+sortOrder+pageSize) +".json.gz";
        final var path = UUID.randomUUID () + "-" + fileName;
        final var fileOutputStream = new FileOutputStream ( path );
        final var gzipOutputStream = new GZIPOutputStream ( fileOutputStream );

        final var mapper = DatabindCodec.mapper ();
        final var jsonGenerator = mapper.getFactory ().createGenerator ( gzipOutputStream, JsonEncoding.UTF8 );
        jsonGenerator.writeStartArray ();

                    log.info ( "Selected pageSize {}", pageSize );
                    log.info ( "sorted by {}", sortField );
                    return select ( pageSize, sortField, sortOrder )
                            .toFlowable ()
                            .map ( row -> row.getString ( 0 ) )
                            .doOnNext ( node->mapper.writeValue ( jsonGenerator,node ) )
                            .flatMapSingle ( ds->service.prtRant ( JsonArray.of ( ds ) ) )
                            .ignoreElements ()
                            .doOnTerminate ( ()->{
                                jsonGenerator.writeEndArray ();
                                jsonGenerator.close ();
                                gzipOutputStream.close ();
                                fileOutputStream.close ();
                            } )
                            .toSingleDefault ( FileResponse.builder ()
                                    .path ( path )
                                    .fileName ( fileName )
                                    .build ());

    });
}

and this is my select code

public Single<JsonArray> select(int pageSize, String sortField, String sortOrder) {
    final var statement = QueryBuilder.selectFrom ( "marketplace", "bankgateway_transaction" )
            .json ()
            .all ()
            .build ()
            .setPageSize ( pageSize );

    final var fetch= cqlSessionSingle.flatMap ( cqlSession -> Single.fromFuture ( cqlSession.executeAsync ( statement ).toCompletableFuture ()))
            .map(AsyncPagingIterable::currentPage)
            .flatMapObservable(Observable::fromIterable)
            .map(row -> row.getString(0))
            .toList();
    final var partitioning = fetch.flatMap ( data->service.prtRant ( JsonArray.of ( data ) ) ).map(JsonArray::new);

    return partitioning;
}

one make a call to a cassandra DB and then transform it into list then partitioned and then into a JsonArray to make it more easy to manage on the web, then the download method is call
and this is the partitioning method

private Single<List<Long>> pTinter(Long count) {

    final var  parZ = cPZ(count);
    final var tPar = cTP(count, parZ);
    return Single.zip(tPar,parZ, (total, size) -> {
        //Implementacion de la logica de particion
            List<Long> PartitionId = new ArrayList<>();
            for (long i = 0; i < total; i++) {

                PartitionId.add(i*size);
            }
            // Ordenar las particiones según el criterio de clasificación proporcionado

        return new ArrayList<> ( PartitionId );
    });
}

Like it look, i partitioned a JsonArray and then write the content on a fileOutput wich gonna be hashed and has a .json.gz type, im expecting the partitioning and get a file less than the original, but im getting a file much bigger