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[Aaron Wells <1081947@xxxxxxxxxxxxxxxxxx>]

** Changed in: mahara
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1081947

Title:
  Use of CAST() causes extreme slowdown in large MySQL sites

Status in Mahara ePortfolio:
  Fix Released
Status in Mahara 1.6 series:
  In Progress
Status in Mahara 1.7 series:
  In Progress
Status in Mahara 1.8 series:
  Fix Committed
Status in Mahara 1.9 series:
  Fix Released

Bug description:
  Mahara version  1.5.2
  Linux CentOS release 5.8
  PHP Version 5.3.15
  MySQL 5.0.77 

  When editing a page and trying to add a normal text box by dragging it
  into the page, this loads for approx 2 minutes or more and then
  eventually appears.

  It happens with a journal too but all others are fine and are instant
  as they should be.

  I'm not getting any apache log errors for this nor general server
  errors. The only thing I am able to see is the query that it hangs on
  for this length of time.... it is the below...

  I hope someone can help as obviously this is causing quite a lot of
  issues for the users!! Anyone able to diagnose what is the issue here?

  The thing is, there is another exact version of the Mahara site
  alongside this one but just a blank version which runs perfectly fine
  so this must be an issue within the database somewhere or the
  maharadata.

  Query below: this hangs for about 1 minute 45..

  SELECT a.*, CAST(a.owner IS NOT NULL AND a.owner = '1739' AS UNSIGNED) AS editable FROM "artefact" a
              LEFT OUTER JOIN "artefact_parent_cache" apc ON (a.id = apc.artefact AND a.institution = 'mahara' AND apc.parent = 371) WHERE (
                  a.owner = '1739'
                  OR a.id IN (
                      SELECT aar.artefact
                      FROM "group_member" m
                          JOIN "artefact" aa ON m.group = aa.group
                          JOIN "artefact_access_role" aar ON aar.role = m.role AND aar.artefact = aa.id
                      WHERE m.member = '1739' AND aar.can_republish = 1
                  )
                  OR a.id IN (SELECT artefact FROM "artefact_access_usr" WHERE usr = '1739' AND can_republish = 1)
                  OR a.institution IN ('test','mahara')
              ) AND artefacttype IN('blog')ORDER BY title ASC LIMIT 10 |

  Then this one for the rest of the time until eventually the text box
  or journal appears on the page:

  SELECT COUNT(*)  FROM "artefact" a
              LEFT OUTER JOIN "artefact_parent_cache" apc ON (a.id = apc.artefact AND a.institution = 'mahara' AND apc.parent = 371) WHERE (
                  a.owner = '1739'
                  OR a.id IN (
                      SELECT aar.artefact
                      FROM "group_member" m
                          JOIN "artefact" aa ON m.group = aa.group
                          JOIN "artefact_access_role" aar ON aar.role = m.role AND aar.artefact = aa.id
                      WHERE m.member = '1739' AND aar.can_republish = 1
                  )
                  OR a.id IN (SELECT artefact FROM "artefact_access_usr" WHERE usr = '1739' AND can_republish = 1)
                  OR a.institution IN ('test','mahara')
              ) AND artefacttype IN('blogpost') |

  Thank you for your help

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