Derby
  1. Derby
  2. DERBY-4327

Implement optimizer support for bushy trees.

    Details

    • Type: Improvement Improvement
    • Status: Open
    • Priority: Major Major
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: SQL
    • Urgency:
      Normal
    • Bug behavior facts:
      Performance, Seen in production

      Description

      Currently, the optimizer only considers left-deep trees. For queries involving many tables, the best plan may be bushy. In this email thread, a user notes poor performance by Derby on queries involving 5 or more tables: http://www.nabble.com/Slow-performance-on-5-or-more-joins-in-a-star-schema-tt24708686.html

        Issue Links

          Activity

          Show
          Dag H. Wanvik added a comment - - edited Some links: https://www.simple-talk.com/sql/performance/join-reordering-and-bushy-plans/ http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDwQFjAA&url=http%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fdownload%3Fdoi%3D10.1.1.56.6379%26rep%3Drep1%26type%3Dpdf&ei=3GUoUtbTN8uQ0QWh0oDYAw&usg=AFQjCNFme8BiQI59ZnxP68M6cnY0Pzr_cA&bvm=bv.51773540,d.d2k&cad=rja
          Ramin Baradari made changes -
          Comment [ Sehr geehrte Damen und Herren,

          vielen Dank für Ihre Nachricht. Ich bin ab 1. Oktober 2012 wieder im Haus. Meine E-Mails werden nicht weitergeleitet und erst dann beantwortet. In dringenden Fällen wenden Sie sich bitte an Robert Buchwald unter der E-Mail-Adresse r.buchwald@4flow.de.

          Mit freundlichen Grüßen
          Ramin Baradari


          Dear Sir or Madam:

          Thank you very much for your email. I will be out of the office until October 1, 2012. I will answer your email upon my return. Please note that your email will not be forwarded during this time. In urgent cases, please do not hesitate to contact Robert Buchwald, r.buchwald@4flow.com.

          Best regards
          Ramin Baradari
          ]
          Gavin made changes -
          Workflow jira [ 12471826 ] Default workflow, editable Closed status [ 12797158 ]
          Mamta A. Satoor made changes -
          Labels derby_triage10_10
          Hide
          Nirmal Fernando added a comment -

          Hi Rick,

          Thanks for the reply!

          Show
          Nirmal Fernando added a comment - Hi Rick, Thanks for the reply!
          Hide
          Rick Hillegas added a comment -

          Hi Nirmal,

          My sense is that this is a tricky issue with a large risk of destabilizing existing applications. The fallout from this change would be felt over many subsequent releases. I would not recommend this as a GSoC project or as someone's first introduction to the Derby optimizer. Thanks.

          Show
          Rick Hillegas added a comment - Hi Nirmal, My sense is that this is a tricky issue with a large risk of destabilizing existing applications. The fallout from this change would be felt over many subsequent releases. I would not recommend this as a GSoC project or as someone's first introduction to the Derby optimizer. Thanks.
          Hide
          Nirmal Fernando added a comment -

          Hi,

          I am really interested in this issue! I am wondering whether this is a suitable project as a GSoC project?

          Thanks!

          Show
          Nirmal Fernando added a comment - Hi, I am really interested in this issue! I am wondering whether this is a suitable project as a GSoC project? Thanks!
          Rick Hillegas made changes -
          Field Original Value New Value
          Link This issue is related to DERBY-1907 [ DERBY-1907 ]
          Rick Hillegas created issue -

            People

            • Assignee:
              Unassigned
              Reporter:
              Rick Hillegas
            • Votes:
              2 Vote for this issue
              Watchers:
              2 Start watching this issue

              Dates

              • Created:
                Updated:

                Development