zanmato1984 commented on code in PR #45330:
URL: https://github.com/apache/arrow/pull/45330#discussion_r1950285780
##########
cpp/src/arrow/dataset/file_parquet.cc:
##########
@@ -835,6 +836,10 @@ Status ParquetFileFragment::SetMetadata(
DCHECK_EQ(manifest_->descr, original_metadata_->schema())
<< "SchemaDescriptor should be owned by the original FileMetaData";
+ if (!physical_schema_) {
+ physical_schema_ = given_physical_schema_;
Review Comment:
Could elaborate a bit about why this change?
##########
cpp/src/arrow/dataset/file_parquet.cc:
##########
@@ -802,12 +802,13 @@ Status
ParquetFileFragment::EnsureCompleteMetadata(parquet::arrow::FileReader* r
return EnsureCompleteMetadata(reader.get());
}
+ // TODO temp variable is useless
Review Comment:
What does this TODO mean?
##########
cpp/src/arrow/dataset/scanner_test.cc:
##########
@@ -922,6 +923,22 @@ std::ostream& operator<<(std::ostream& out, const
TestScannerParams& params) {
return out;
}
+// An InMemoryFragment subclass that tracks the calls to ClearCachedMetadata()
+class ClearCachedMetadataFragment : public InMemoryFragment {
+ public:
+ using InMemoryFragment::InMemoryFragment;
+
+ Status ClearCachedMetadata() override {
+ metadata_clear_count_.fetch_add(1);
Review Comment:
Maybe we should invoke the actual `ClearCachedMetadata()` to do some real
clearing?
##########
cpp/src/arrow/dataset/scanner.cc:
##########
@@ -318,10 +319,14 @@ Result<EnumeratedRecordBatchGenerator> FragmentToBatches(
RecordBatch::Make(options->dataset_schema, /*num_rows=*/0,
std::move(columns)));
auto enumerated_batch_gen = MakeEnumeratedGenerator(std::move(batch_gen));
- auto combine_fn =
- [fragment](const Enumerated<std::shared_ptr<RecordBatch>>& record_batch)
{
- return EnumeratedRecordBatch{record_batch, fragment};
- };
+ auto combine_fn = [fragment, cache_metadata = options->cache_metadata](
+ const Enumerated<std::shared_ptr<RecordBatch>>&
record_batch) {
+ if (!cache_metadata && record_batch.last) {
+ ARROW_WARN_NOT_OK(fragment.value->ClearCachedMetadata(),
+ "Could not clear cached metadata on fragment");
+ }
Review Comment:
This is OK but I wonder can we extend `MappedGenerator` by accepting an
optional continuation to be invoked once the generator is exhausted? Then we
can clear the cached metadata in that continuation - not having to check the
last-ness of the record batch.
##########
cpp/src/arrow/dataset/scanner_test.cc:
##########
@@ -922,6 +923,22 @@ std::ostream& operator<<(std::ostream& out, const
TestScannerParams& params) {
return out;
}
+// An InMemoryFragment subclass that tracks the calls to ClearCachedMetadata()
+class ClearCachedMetadataFragment : public InMemoryFragment {
+ public:
+ using InMemoryFragment::InMemoryFragment;
+
+ Status ClearCachedMetadata() override {
+ metadata_clear_count_.fetch_add(1);
Review Comment:
```suggestion
RETURN_NOT_OK(InMemoryFragment::ClearCachedMetadata());
metadata_clear_count_.fetch_add(1);
```
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