Bug fix: should not write single index block

Author: Nitsan Wakart

src/java/org/apache/cassandra/io/sstable/SSTableCursorWriter.java

@@ -203,12 +203,15 @@ private void appendBIGIndex(byte[] key, int keyLength, long partitionStart, int
             ByteArrayUtil.writeWithShortLength(key, 0, keyLength, indexFileWriter);
 
             indexFileWriter.writeUnsignedVInt(partitionStart);
-            if (rowIndexEntriesOffsets.isEmpty())
+
+            // if the list of entries has one or fewer entries, no point in index entries.
+            /** See: {@link org.apache.cassandra.io.sstable.format.big.RowIndexEntry#create} */
+            if (rowIndexEntriesOffsets.size() <= 1)
             {
                 /**
                  * {@link RowIndexEntry#serialize(DataOutputPlus, ByteBuffer)}
                  */
-                indexFileWriter.writeUnsignedVInt32(0);
+                indexFileWriter.writeUnsignedVInt32(0); // size
             }
             else {
                 // add last block
@@ -223,11 +226,14 @@ private void appendBIGIndex(byte[] key, int keyLength, long partitionStart, int
                 // Write the headerLength, partitionDeletionTime and rowIndexEntriesOffsets.size() after the entries,
                 // just to calculate size.
                 rowIndexEntries.writeUnsignedVInt((long)headerLength);
-                this.deletionTimeSerializer.serialize(partitionDeletionTime, rowIndexEntries);
-                rowIndexEntries.writeUnsignedVInt32(rowIndexEntriesOffsets.size());
+                deletionTimeSerializer.serialize(partitionDeletionTime, rowIndexEntries);
+
+                rowIndexEntries.writeUnsignedVInt32(rowIndexEntriesOffsets.size()); // number of entries
 
                 // bytes until offsets
-                indexFileWriter.writeUnsignedVInt32(rowIndexEntries.getLength() + rowIndexEntriesOffsets.size() * 4);
+                int entriesAndOffsetsSize = rowIndexEntries.getLength() + rowIndexEntriesOffsets.size() * 4;
+                assert entriesAndOffsetsSize > 0;
+                indexFileWriter.writeUnsignedVInt32(entriesAndOffsetsSize); // size != 0
                 // copy the header elements
                 indexFileWriter.write(rowIndexEntries.getData(), endOfEntries, rowIndexEntries.getLength() - endOfEntries);
                 indexFileWriter.write(rowIndexEntries.getData(), 0, endOfEntries);