Results 1 to 2 of 2
  1. #1
    Join Date
    Apr 2012
    Posts
    156

    Unanswered: DB2 11.0 Column Organized Table Performance Issue

    Hello,
    I am doing a POC on using BLU and am seeing really poor performance when doing a groupby on a varchar column. Here is the scenario:
    1. Select count(1), varchar_column from column_organized_table group by varchar_column; <-- run time 10 minutes on a 20 million row table (fairly small)
    2. Select count(1), integer_column from column_organized_table group by integer_column; <-- run time less than 2 seconds
    1. Select count(1), varchar_column from row_organized_table group by varchar_column; <-- run time 40 seconds on a 20 million row table (fairly small)

    I am seeing great performance for our star schema joins which of course are not joining on varchar columns. However anytime I try to run queries based on a varchar column performance is horrendous. Has anyone encountered this issue? I can't find any documentation that says that a varchar column will have poor performance.

  2. #2
    Join Date
    Oct 2007
    Posts
    162
    Provided Answers: 9
    what is the difference on the 2 varchar columns you gave as examples? What are their lengths? does this SQL eliminate any duplication?

Posting Permissions

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