pitrou commented on code in PR #45252:
URL: https://github.com/apache/arrow/pull/45252#discussion_r1914771344
##########
cpp/src/parquet/column_writer_test.cc:
##########
@@ -1774,5 +1774,29 @@ TEST_F(TestInt32Writer, WriteKeyValueMetadataEndToEnd) {
ASSERT_EQ("bar", value);
}
+TEST_F(TestValuesWriterInt32Type, AllNullsInPageV2) {
+#ifndef ARROW_WITH_SNAPPY
+ GTEST_SKIP() << "Test requires snappy compression";
+#endif
+ // Optional and non-repeated, with definition levels
+ // but no repetition levels
+ this->SetUpSchema(Repetition::OPTIONAL);
+ this->GenerateData(SMALL_SIZE);
+ std::fill(this->def_levels_.begin(), this->def_levels_.end(), 0);
+ ColumnProperties column_properties;
+ column_properties.set_compression(Compression::SNAPPY);
Review Comment:
Why not test all compression algorithms?
##########
cpp/src/parquet/column_reader.cc:
##########
@@ -580,13 +580,20 @@ std::shared_ptr<Buffer>
SerializedPageReader::DecompressIfNeeded(
memcpy(decompressed, page_buffer->data(), levels_byte_len);
}
- // Decompress the values
- PARQUET_ASSIGN_OR_THROW(
- auto decompressed_len,
- decompressor_->Decompress(compressed_len - levels_byte_len,
- page_buffer->data() + levels_byte_len,
- uncompressed_len - levels_byte_len,
- decompression_buffer_->mutable_data() +
levels_byte_len));
+ // GH-31992: DataPageV2 may store only levels and no values
Review Comment:
Can we fix this in the Snappy decompressor instead?
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