anchor.diff:      
   module Reader =
       let simpleQuery indices fileName =
  -        SimpleReadWrite.readValues fileName indices
  -        //MemoryMappedSimpleRead.readValues fileName indices
  +        //SimpleReadWrite.readValues fileName indices
  +        MemoryMappedSimpleRead.readValues fileName indices
   
       let sparseQuery indices fileName =
           SparseReadWrite.readValues fileName indices
  
positive.code:         let root = @"D:\a\data\marspec\MARSPEC_10m\ascii\"
          let paths = Directory.GetFiles(root, "*.asc")
          testSimpleRandom "test simple AllMarspec10m" paths 100 1000 |> ignore
          // 39s 10000 * 10
          // 22s 1000 * 100
          // 17s 100 * 1000
  
negative.code:         for i=0 to len-1 do
              sw.Restart()
              let indices = [1..innerlen] |> List.map (fun i -> (int64 (r.Next(0, 2160*1080)) ))
              let indices = indices.OrderBy(fun x -> x)
              result <- Array.map (query indices) sbgPaths
              sw.Stop()
              arr.[i] <- sw.ElapsedMilliseconds
  