emkornfield commented on code in PR #14964:
URL: https://github.com/apache/arrow/pull/14964#discussion_r1083090721
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cpp/src/parquet/page_index.h:
##########
@@ -126,4 +132,94 @@ class PARQUET_EXPORT OffsetIndex {
virtual const std::vector<PageLocation>& page_locations() const = 0;
};
+/// \brief Interface for reading the page index for a Parquet row group.
+class PARQUET_EXPORT RowGroupPageIndexReader {
+ public:
+ virtual ~RowGroupPageIndexReader() = default;
+
+ /// \brief Read column index of a column chunk.
+ ///
+ /// \param[in] i column ordinal of the column chunk.
+ /// \returns column index of the column or nullptr if it does not exist.
+ /// \throws ParquetException if the index is out of bound.
+ virtual std::shared_ptr<ColumnIndex> GetColumnIndex(int32_t i) = 0;
+
+ /// \brief Read offset index of a column chunk.
+ ///
+ /// \param[in] i column ordinal of the column chunk.
+ /// \returns offset index of the column or nullptr if it does not exist.
+ /// \throws ParquetException if the index is out of bound.
+ virtual std::shared_ptr<OffsetIndex> GetOffsetIndex(int32_t i) = 0;
+};
+
+struct IndexSelection {
+ /// Specifies whether to read the column index.
+ bool column_index = false;
+ /// Specifies whether to read the offset index.
+ bool offset_index = false;
+};
+
+struct RowGroupIndexReadRange {
+ /// Base start and total size of column index of all column chunks in a row
group.
+ /// If none of the column chunks have column index, it is set to
std::nullopt.
+ std::optional<::arrow::io::ReadRange> column_index = std::nullopt;
+ /// Base start and total size of offset index of all column chunks in a row
group.
+ /// If none of the column chunks have offset index, it is set to
std::nullopt.
+ std::optional<::arrow::io::ReadRange> offset_index = std::nullopt;
+};
+
+/// \brief Interface for reading the page index for a Parquet file.
+class PARQUET_EXPORT PageIndexReader {
+ public:
+ virtual ~PageIndexReader() = default;
+
+ /// \brief Create a PageIndexReader instance.
+ /// \returns a PageIndexReader instance.
+ /// WARNING: The returned PageIndexReader references to all the input
parameters, so
+ /// it must not outlive all of the input parameters. Usually these input
parameters
+ /// come from the same ParquetFileReader object, so it must not outlive the
reader
+ /// that creates this PageIndexReader.
+ static std::shared_ptr<PageIndexReader> Make(
+ ::arrow::io::RandomAccessFile* input, std::shared_ptr<FileMetaData>
file_metadata,
+ const ReaderProperties& properties,
+ std::shared_ptr<InternalFileDecryptor> file_decryptor = NULLPTR);
+
+ /// \brief Get the page index reader of a specific row group.
+ /// \param[in] i row group ordinal to get page index reader.
+ /// \returns RowGroupPageIndexReader of the specified row group. A nullptr
may or may
+ /// not be returned if the page index for the row group is
unavailable. It is
+ /// the caller's responsibility to check the return value of
follow-up calls
+ /// to the RowGroupPageIndexReader.
+ /// \throws ParquetException if the index is out of bound.
+ virtual std::shared_ptr<RowGroupPageIndexReader> RowGroup(int i) = 0;
+
+ /// \brief Advise the reader which part of page index will be read later.
+ ///
+ /// The PageIndexReader implementation can optionally prefetch and cache
page index
+ /// that may be read later. Follow-up read should not fail even if
WillNeed() is not
+ /// called, or the requested page index is out of range from WillNeed() call.
+ ///
+ /// \param[in] row_group_indices list of row group ordinal to read page
index later.
+ /// \param[in] index_selection tell if any of the page index is required
later.
+ virtual void WillNeed(const std::vector<int32_t>& row_group_indices,
+ IndexSelection index_selection) = 0;
Review Comment:
nit, even though this might be more effient, probably pays to use const
IndexSelection& as the formal parameter.
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