cost
DBAsupport.com Forums - Powered by vBulletin
Results 1 to 2 of 2

Thread: cost

  1. #1
    Join Date
    Jan 2000
    Location
    san jose
    Posts
    149
    i have a table big_table( a int,b int, c varchar2(100));

    it have 1M rows.


    when i run explain plan for
    insert into big_table values (1,1,'whatever');

    the plan table look like
    --------------------------------------------------------------------------------
    | Operation | Name | Rows | Bytes| Cost | Pstart| Pstop |
    --------------------------------------------------------------------------------
    | INSERT STATEMENT | | 1M| 17M| 540 | | |
    --------------------------------------------------------------------------------

    the cost is 540.

    but if i run same DML on some small table the cost is much cheaper.

    why so much different? if the cost is reasonable bigger, i can understand, but not so much.

  2. #2
    Join Date
    Nov 2000
    Location
    Baltimore, MD USA
    Posts
    1,339
    Unfortunately, the cost value is not so universally applicable. Basically, the cost value *is only* accurate for purposes of the optimizer choosing between multiple paths for the same statement. Change the statement and the cost will no longer be comparable.

    Jurij addressed that in this thread as well...
    http://www.dbasupport.com/forums/sho...threadid=11868

    HTH,

    - Chris

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Click Here to Expand Forum to Full Width