Tickets :: Comment on [#3046] Remove all DataTree usage

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Comment	>> The permission system was one of the main reasons for writing the > >> DataTree backend, and we need a tree structure for permissions. Also, > >> now that history has been moved out, permissions is (almost) the only > >> thing left that uses DataTree. > > > > When we got our performance problem, history was not activated, so > moving out the history would not be enough. The performance problem > with the actual permission implementation arise when there are many > users. Our database server came to a halt after about 4000 users has > logged in. > > > > We found that these type of requests were the main performance problem: > > > > SELECT c.datatree_id, c.datatree_name FROM horde_datatree c LEFT JOIN > > horde_datatree_attributes a1 ON a1.datatree_id = c.datatree_id WHERE > > c.group_uid = 'horde.shares.nag' AND ((a1.attribute_name = 'owner' AND > > a1.attribute_value = 'myuserid') OR (a1.attribute_name = 'perm_users' > > AND a1.attribute_key = 'myuserid' AND a1.attribute_value & > > 2) OR (a1.attribute_name = 'perm_creator' AND a1.attribute_value & 2) OR > > (a1.attribute_name = 'perm_default' AND a1.attribute_value & 2)) > > GROUP BY c.datatree_id, c.datatree_name, c.datatree_order ORDER BY > > c.datatree_order, c.datatree_name, c.datatree_id > > > > When doing an "explain" on the mysql server, it shows that this > request has to evaluate each time a number of entries roughly > proportionnal to the number of users in the database (since each user > has at least one share for each type). If each type of shares had its > own table (horde.shares.nag, horde.shares.kronolith), it would not > have to do the left join and generate a temporary table each time, > and it would probably better use the indexes. > > > > If you have another way (other than changing the database structure > or use session caching) to improve the performance of the permission > system with thousands of users, I'm all ears! Right now,we are > stucked with horde 2.2 because of this problem :( > >
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