[Bug 1433924] Re: "Too much data for sort() with no index." While Getting Resources

[Thierry Carrez]

** Changed in: ceilometer
    Milestone: liberty-3 => 5.0.0

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https://bugs.launchpad.net/bugs/1433924

Title:
  "Too much data for sort() with no index." While Getting Resources

Status in Ceilometer:
  Fix Released
Status in ceilometer package in Ubuntu:
  Fix Released
Status in ceilometer source package in Trusty:
  Triaged
Status in ceilometer source package in Vivid:
  Triaged
Status in ceilometer source package in Wily:
  Fix Released

Bug description:
  We have 47GB of mongo data. When I run "ceilometer resource-list", I
  get the error in the subject. I isolated the problem down to
  storage/impl_mongodb.py:746 _get_floating_resources(). It builds an
  empty query with sort options "{user_id: -1, project_id: -1,
  last_sample_timestamp: -1}" and it fails.

  I ran the query in mongodb to see if it was generating the same error
  and confirmed it. After a bit digging, I learned that mongodb needs
  compound index for that kind of sort. I added the following index via
  mongocl:

  db.resource.createIndex({user_id: -1, project_id: -1,
  last_sample_timestamp: -1}, {background: true})

  After this index, the problem went away. I can run "ceilometer
  resource-list" and "ceilometer meter-list". However, those commands
  take ~1minute to complete with the index. The performance may be
  another issue that needs investigation.

  I need to mention that this error is different than
  https://bugs.launchpad.net/ceilometer/+bug/1193906. The timestamp
  index is in place but we need compound indexes as I explained above.

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