title: compare B+tree implementation: storing internal nodes on disk
body: <p>is there any implementation where internal nodes of B+tree is also stored on disk? I am just wondering if any one is aware of such an implementation or see real advantage doing it this way? Normally, one stores the leaf nodes on disk and develop the B+ tree as per need.</p>
  
  <p>But it is also possible to save the current state of B+tree's internal nodes (by replacing the pointers by disk block number it points to): I see there are other challenges like keeping the internal nodes in memory in sync with the disk blocks: but the B+ tree may be implemented on nvram or say battery backed dram or some other method to keep it in sync.</p>
  
  <p>Just wondering if anyone has already implemented it this way like linux's bcache or another implementation?</p>
  
  <p>cheers, cforfun!</p>