+++ This bug was initially created as a clone of Bug #1254003 +++

Description of problem:
Deadlock in user sync causes failures in collections and aggregation. The users details sync is done every minute it lock the row for update, once a hour the hourly aggregation tries to sync VM data containing users foreign key which causes deadlock due to wait on the users table update.

See Thread about this issue:
http://stackoverflow.com/questions/18536147/deadlock-involving-foreign-key-constraint

and fix in 9.3 for this:
http://michael.otacoo.com/postgresql-2/postgres-9-3-feature-highlight-for-key-share-and-for-no-key-update/

Version-Release number of selected component (if applicable):
3.5.0

How reproducible:
always

Steps to Reproduce:
1. add many users to engine.
2. use users on some vm.
3. waiting a few hours for aggregation to start

Actual results:
Deadlock between aggregation (due to foreign keys) and collection.

Expected results:
Should not deadlock.

--- Additional comment from Yaniv Dary on 2015-08-16 09:45:01 EDT ---



--- Additional comment from Yaniv Dary on 2015-08-16 09:53:16 EDT ---



--- Additional comment from Yaniv Dary on 2015-08-16 10:42:11 EDT ---

To unblock 3.5 users that might hit this, we will remove the foreign key completely. For 3.6 we will try to find a better way to fix this, maybe by reducing the amount of updates done in each time.