1 files changed, 2 insertions, 1 deletions
diff --git a/db/extsort.cpp b/db/extsort.cpp
index 949c2e66500..751c63e650f 100644
--- a/db/extsort.cpp
+++ b/db/extsort.cpp
@@ -204,7 +204,8 @@ namespace mongo {
     
     BSONObjExternalSorter::FileIterator::FileIterator( string file ){
         long length;
-        _buf = (char*)_file.map( file.c_str() , length );
+        _buf = (char*)_file.map( file.c_str() , length , MemoryMappedFile::SEQUENTIAL );
+        massert( "mmap failed" , _buf );
         assert( (unsigned long)length == file_size( file ) );
         _end = _buf + length;
     }