mahara-contributors team mailing list archive

[Hugh Davenport <817796@xxxxxxxxxxxxxxxxxx>]

I don't think we can get any more optimized for MySQL.

MySQL doesn't have UPDATE FROM sql syntax (like what was done with the
postgres optimization).

Another option would be to do an UPDATE and a SELECT query inside the SET clause, but from the page http://dev.mysql.com/doc/refman/5.6/en/update.html down the bottom we have the following:
"Currently, you cannot update a table and select from the same table in a subquery."

This basically means we can't update the group table without SELECTing
the needed information before hand. Doing it this way makes a bulk
UPDATE statement difficult. Because of this, I think we should just keep
as is for mysql upgrades.

Thoughts?

Cheers,

Hugh

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https://bugs.launchpad.net/bugs/817796

Title:
  Slow upgrades for profile icons & group quotas

Status in Mahara ePortfolio:
  Incomplete

Bug description:
  Three recent upgrades are very slow on large databases and are in need
  of a bit of a rewrite:

  - The upgrade to remove bad profileicon references from the user table
  - The upgrade to initialise group file quotas
  - The upgrade which moves existing profileicons into an 'images' folder.

  https://reviews.mahara.org/#change,528

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