litao3rd commented on issue #37840:
URL: https://github.com/apache/arrow/issues/37840#issuecomment-1734931672
> ```c++
> arrow::Status status;
> fs::FileSelector selector;
> selector.base_dir = base_dir;
> selector.recursive = true;
> auto factory = ds::FileSystemDatasetFactory::Make(filesystem, selector,
format, ds::FileSystemFactoryOptions())
> .ValueOrDie();
> ds::FinishOptions finishOptions;
> ::arrow::SchemaBuilder builder;
> auto s = builder.AddField(::arrow::field("dispatching_base_num",
::arrow::large_utf8()));
> if (!s.ok()) {
> s.Abort();
> }
> s =builder.AddField(::arrow::field("pickup_datetime",
::arrow::timestamp(::arrow::TimeUnit::SECOND)));
> s =builder.AddField(::arrow::field("dropoff_datetime",
::arrow::timestamp(::arrow::TimeUnit::SECOND)));
> s =builder.AddField(::arrow::field("PULocationID", ::arrow::int32()));
> s =builder.AddField(::arrow::field("DOLocationID", ::arrow::int32()));
> s =builder.AddField(::arrow::field("SR_Flag", ::arrow::int32()));
> s =builder.AddField(::arrow::field("dispatching_base_number",
::arrow::large_utf8()));
> if (!s.ok()) {
> s.Abort();
> }
> finishOptions.schema = builder.Finish().ValueOrDie();
> auto dataset = factory->Finish(finishOptions).ValueOrDie();
> auto sb = dataset->NewScan().ValueOrDie();
> s = sb->UseThreads(false);
> if (!s.ok()) {
> s.Abort();
> }
> auto scanner = sb->Finish().ValueOrDie();
> {
> // In this block I got total 57410540 rows
> int64_t total_rows = 0;
> if (scanner->options()->dataset_schema != nullptr) {
> std::cout << "Schema: " <<
scanner->options()->dataset_schema->ToString() << std::endl;
> } else {
> std::cout << "Schema: " << "NONE" << std::endl;
> }
> status = scanner->Scan([&](ds::TaggedRecordBatch batch) ->
arrow::Status {
> total_rows += batch.record_batch->num_rows();
> return arrow::Status::OK();
> });
> std::cout << "total count rows in visitor mode = " << total_rows << ",
result:" << status.ToString() << "\n";
> }
> {
> // In this block I got total 1526807659 rows
> std::cout << "total count rows() = " <<
scanner->CountRows().ValueOrDie() << "\n";
> }
> return 0;
> ```
>
> remember to check the `status` after computing
Greate! Thanks for your reply. It's really helpful for me.
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