Re: How can i get record by data block not by sql?

Craig Ringer <ringerc@xxxxxxxxxxxxx> · Tue, 04 Oct 2011 10:57:39 +0800



    On 03/10/11 17:03, ˝ŞÍ· wrote:
    
      
      How can i get record by data block not by sql?
       
      I want to read and write lots of data by data blocks, so i
        can form a disk-resident tree by recording the block address.
        But i don't know  how to implement in postgresql. 
      Is there system function can do this? 

      
    It might be a good idea to take a step or three back and ask: "Why?"

    
    What are you trying to achieve? What is the goal?

    
    Is PostgreSQL the right choice? Have you looked at lower-level
    databases like Berkeley DB, various raw ISAM engines, etc? For that
    matter, if you want block-level operation, don't you really just
    want pread() and pwrite()?

    
    If you want to do something within the PostgreSQL engine using your
    own custom files to store data, you would have to do it by writing C
    functions as server-side extensions and calling those via SQL to
    access and manage your data. These functions would have to use their
    own separate data; they could **NOT** safely use existing postgresql
    data files in any way.

    
    --

    Craig Ringer