wgtmac commented on code in PR #42133:
URL: https://github.com/apache/arrow/pull/42133#discussion_r1639154343
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cpp/src/parquet/arrow/reader_internal.cc:
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@@ -330,15 +331,30 @@ Status TransferInt(RecordReader* reader, MemoryPool* pool,
auto values = reinterpret_cast<const ParquetCType*>(reader->values());
auto out_ptr = reinterpret_cast<ArrowCType*>(data->mutable_data());
std::copy(values, values + length, out_ptr);
+ int64_t null_count = 0;
+ std::vector<std::shared_ptr<Buffer>> buffers = {nullptr, std::move(data)};
if (field->nullable()) {
- *out = std::make_shared<ArrayType<ArrowType>>(field->type(), length,
std::move(data),
- reader->ReleaseIsValid(),
- reader->null_count());
- } else {
- *out =
- std::make_shared<ArrayType<ArrowType>>(field->type(), length,
std::move(data),
- /*null_bitmap=*/nullptr,
/*null_count=*/0);
+ null_count = reader->null_count();
+ buffers[0] = reader->ReleaseIsValid();
+ }
+ auto array_data =
+ ::arrow::ArrayData::Make(field->type(), length, std::move(buffers),
null_count);
+ array_data->statistics.null_count = null_count;
+ auto statistics = metadata->statistics().get();
+ if (statistics) {
+ if (statistics->HasDistinctCount()) {
+ array_data->statistics.distinct_count = statistics->distinct_count();
+ }
+ if (statistics->HasMinMax()) {
+ auto typed_statistics =
+ static_cast<::parquet::TypedStatistics<ParquetType>*>(statistics);
+ array_data->statistics.min_buffer =
+ static_cast<ArrowCType>(typed_statistics->min());
+ array_data->statistics.max_buffer =
+ static_cast<ArrowCType>(typed_statistics->max());
+ }
}
+ *out = std::make_shared<ArrayType<ArrowType>>(std::move(array_data));
Review Comment:
In an extreme case, users might read a parquet file containing two row
groups in a single `arrow::Table`, we have to merge the column statistics,
right?
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