Merge src/leveldb changes: temporarily revert to writing .sst files.

src/leveldb/db/filename.cc

@@ -29,14 +29,19 @@ std::string LogFileName(const std::string& name, uint64_t number) {
   return MakeFileName(name, number, "log");
 }
 
+// TableFileName returns the filenames we usually write to, while
+// SSTTableFileName returns the alternative filenames we also try to read from
+// for backward compatibility. For now, swap them around.
+// TODO: when compatibility is no longer necessary, swap them back
+// (TableFileName to use "ldb" and SSTTableFileName to use "sst").
 std::string TableFileName(const std::string& name, uint64_t number) {
   assert(number > 0);
-  return MakeFileName(name, number, "ldb");
+  return MakeFileName(name, number, "sst");
 }
 
 std::string SSTTableFileName(const std::string& name, uint64_t number) {
   assert(number > 0);
-  return MakeFileName(name, number, "sst");
+  return MakeFileName(name, number, "ldb");
 }
 
 std::string DescriptorFileName(const std::string& dbname, uint64_t number) {