Added StripeColumnStatistics from Metadata section.

Author: ddrinka

src/ApacheOrcDotNet.OptimizedReader/OrcReader.cs

@@ -57,6 +57,11 @@ public ColumnStatistics GetFileColumnStatistics(int columnId)
             return _fileTail.Footer.Statistics[columnId];
         }
 
+        public ColumnStatistics GetStripeColumnStatistics(int columnId, int stripeId)
+        {
+            return _fileTail.Metadata.StripeStats[stripeId].ColStats[columnId];
+        }
+
         public IEnumerable<RowGroupDetail> ReadRowGroupIndex(int columnId, int stripeId)
         {
             if(!_stripeStreams.TryGetValue(stripeId, out var streamDetails))

src/ApacheOrcDotNet.OptimizedReader/SpanFileTail.cs

@@ -9,6 +9,7 @@ public sealed class SpanFileTail
     {
         public Protocol.PostScript PostScript { get; private init; }
         public Protocol.Footer Footer { get; private init; }
+        public Protocol.Metadata Metadata { get; private init; }
 
         public static bool TryRead(ReadOnlySpan<byte> buffer, out SpanFileTail fileTail, out int additionalBytesRequired)
         {
@@ -36,22 +37,30 @@ public static bool TryRead(ReadOnlySpan<byte> buffer, out SpanFileTail fileTail,
                 throw new InvalidDataException("Postscript didn't contain magic bytes");
 
             accumulatedLength += (int)postScript.FooterLength;
+            int footerStart = buffer.Length - accumulatedLength;
+            accumulatedLength += (int)postScript.MetadataLength;
+            int metadataStart = buffer.Length - accumulatedLength;
+
             if (buffer.Length < accumulatedLength)
             {
                 additionalBytesRequired = accumulatedLength - buffer.Length;
                 fileTail = null;
                 return false;
             }
 
-            int footerStart = buffer.Length - accumulatedLength;
             var compressedFooter = buffer.Slice(footerStart, (int)postScript.FooterLength);
-            using var decompressedMemorySequence = new DecompressingMemorySequence(compressedFooter, postScript.Compression, (int)postScript.CompressionBlockSize);
-            var footer = Serializer.Deserialize<Protocol.Footer>(decompressedMemorySequence.Sequence);
+            using var decompressedFooterSequence = new DecompressingMemorySequence(compressedFooter, postScript.Compression, (int)postScript.CompressionBlockSize);
+            var footer = Serializer.Deserialize<Protocol.Footer>(decompressedFooterSequence.Sequence);
+
+            var compressedMetadata = buffer.Slice(metadataStart, (int)postScript.MetadataLength);
+            using var decompressedMetadataSequence = new DecompressingMemorySequence(compressedMetadata, postScript.Compression, (int)postScript.CompressionBlockSize);
+            var metadata = Serializer.Deserialize<Protocol.Metadata>(decompressedMetadataSequence.Sequence);
 
             fileTail = new SpanFileTail
             {
                 PostScript = postScript,
-                Footer = footer
+                Footer = footer,
+                Metadata = metadata
             };
             additionalBytesRequired = 0;
             return true;

test/ApacheOrcDotNet.OptimizedReader.Test/Data/orctest_fromEnd_1942_1942.orc

@@ -53,6 +53,20 @@ public void FileColumnStatistics()
             Assert.Equal(72041.725554m, decimal.Parse(reader.GetFileColumnStatistics(5).DecimalStatistics.Maximum));
         }
 
+        [Fact]
+        public void StripeColumnStatistics()
+        {
+            var reader = new OrcReader(new OrcReaderConfiguration(), _byteRangeProvider);
+            Assert.Equal("BZX", reader.GetStripeColumnStatistics(1, 0).StringStatistics.Minimum);
+            Assert.Equal("BZX", reader.GetStripeColumnStatistics(1, 0).StringStatistics.Maximum);
+            Assert.Equal(1, reader.GetStripeColumnStatistics(2, 0).IntStatistics.Minimum);
+            Assert.Equal(35, reader.GetStripeColumnStatistics(2, 0).IntStatistics.Maximum);
+            Assert.Equal(311, reader.GetStripeColumnStatistics(3, 0).IntStatistics.Minimum);
+            Assert.Equal(16690225, reader.GetStripeColumnStatistics(3, 0).IntStatistics.Maximum);
+            Assert.Equal(25200.063318m, decimal.Parse(reader.GetStripeColumnStatistics(5, 0).DecimalStatistics.Minimum));
+            Assert.Equal(71979.49409m, decimal.Parse(reader.GetStripeColumnStatistics(5, 0).DecimalStatistics.Maximum));
+        }
+
         [Fact]
         public void RowGroupStatistics()
         {

test/ApacheOrcDotNet.OptimizedReader.Test/Data/orctest_fromEnd_20178_20178.orc

@@ -16,6 +16,9 @@ public TestByteRangeProvider(bool writeRequestedRangesToFile, bool readRequested
         {
             _writeRequestedRangesToFile = writeRequestedRangesToFile;
             _readRequestedRangesFromFile = readRequestedRangesFromFile;
+
+            if (_writeRequestedRangesToFile == true && _readRequestedRangesFromFile == true)
+                throw new InvalidOperationException("Cannot read and write to range files simultaneously");
         }
 
         public void Dispose()