[GitHub] [arrow] wgtmac commented on a diff in pull request #36192: PARQUET-2316: [C++] Allow partial PreBuffer in the parquet FileReader

["wgtmac (via GitHub)" <gi...@apache.org>]

wgtmac commented on code in PR #36192:
URL: https://github.com/apache/arrow/pull/36192#discussion_r1241001888


##########
cpp/src/parquet/arrow/arrow_reader_writer_test.cc:
##########
@@ -2382,6 +2382,34 @@ TEST(TestArrowReadWrite, WaitCoalescedReads) {
   ASSERT_EQ(actual_batch->num_rows(), num_rows);
 }
 
+// Use coalesced reads and non-coaleasced reads for different column chunks.
+TEST(TestArrowReadWrite, CoalescedReadsAndNonCoalescedReads) {
+  const int num_columns = 5;
+  const int num_rows = 128;

Review Comment:
   ```suggestion
     constexpr int num_columns = 5;
     constexpr int num_rows = 128;
   ```



##########
cpp/src/parquet/arrow/arrow_reader_writer_test.cc:
##########
@@ -2382,6 +2382,34 @@ TEST(TestArrowReadWrite, WaitCoalescedReads) {
   ASSERT_EQ(actual_batch->num_rows(), num_rows);
 }
 
+// Use coalesced reads and non-coaleasced reads for different column chunks.
+TEST(TestArrowReadWrite, CoalescedReadsAndNonCoalescedReads) {
+  const int num_columns = 5;
+  const int num_rows = 128;
+
+  std::shared_ptr<Table> expected;
+  ASSERT_NO_FATAL_FAILURE(MakeDoubleTable(num_columns, num_rows, 1, &expected));

Review Comment:
   ```suggestion
     ASSERT_NO_FATAL_FAILURE(MakeDoubleTable(num_columns, num_rows, /*nchunks=*/1, &expected));
   ```



##########
cpp/src/parquet/arrow/arrow_reader_writer_test.cc:
##########
@@ -2382,6 +2382,34 @@ TEST(TestArrowReadWrite, WaitCoalescedReads) {
   ASSERT_EQ(actual_batch->num_rows(), num_rows);
 }
 
+// Use coalesced reads and non-coaleasced reads for different column chunks.
+TEST(TestArrowReadWrite, CoalescedReadsAndNonCoalescedReads) {
+  const int num_columns = 5;
+  const int num_rows = 128;
+
+  std::shared_ptr<Table> expected;
+  ASSERT_NO_FATAL_FAILURE(MakeDoubleTable(num_columns, num_rows, 1, &expected));
+
+  std::shared_ptr<Buffer> buffer;
+  ASSERT_NO_FATAL_FAILURE(WriteTableToBuffer(expected, num_rows / 2,
+                                             default_arrow_writer_properties(), &buffer));
+
+  std::unique_ptr<FileReader> reader;
+  ASSERT_OK_NO_THROW(OpenFile(std::make_shared<BufferReader>(buffer),
+                              ::arrow::default_memory_pool(), &reader));
+
+  ASSERT_EQ(2, reader->num_row_groups());
+
+  // Pre-buffer 3 columns in the 2nd row group.
+  reader->parquet_reader()->PreBuffer({1}, {0, 1, 4}, ::arrow::io::IOContext(),
+                                      ::arrow::io::CacheOptions::Defaults());
+  ASSERT_OK(reader->parquet_reader()->WhenBuffered({1}, {0, 1, 4}).status());

Review Comment:
   ```suggestion
     const std::vector<int> row_groups = {1};
     const std::vector<int> column_indices = {0, 1, 4};
     reader->parquet_reader()->PreBuffer(row_groups, column_indices, ::arrow::io::IOContext(),
                                         ::arrow::io::CacheOptions::Defaults());
     ASSERT_OK(reader->parquet_reader()->WhenBuffered(row_groups, column_indices).status());
   ```



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