Exceeding Memory Limit During Measure Calculation

[npm526]

I have been receiving the following error when calculating the aggregate measure calculation.

"Exceeded memory limit for $group, but didnt allow external sort. Pass allowDiskUse:true to opt in"

I am trying to calculate measures for a patient population of approximately 250,000 patients and using the measure calculation API. Has anyone seen this error? Is there a way to set this parameter while using the measure calculation API?

[lrasmus]

@npm526 you will have to modify pophealth, the health-data-standards gem and quality-measure-engine gem for this to work. When you're making aggregate calls in mongo, you will need to set the extra parameter. For example, this line:
https://github.com/OSEHRA/popHealth/blob/master/app/models/patient_cache.rb#L61

Should be changed to read:
Mongoid.default_client.command(aggregate: 'patient_cache', pipeline: pipeline, allowDiskUse: true)['result']

[petercyli]

Hi Luke,
Any reason why this shouldn't be a default setting when making aggregate calls in mongo?

Thanks.

[lrasmus]

Probably worth making it the default now. At the time when I found it, the install guide was using an older version of MongoDB, and this option was only introduced in 2.6 (https://docs.mongodb.com/manual/reference/command/aggregate/)

[petercyli]

Hi Nick,
Can you verify that the fix as suggested by Luke works for you? If so, can you create a pull request with the updated file, and I will merge the code to the master.
Peter

[npm526]

I have implement this fix locally and it has fixed the issue. I submitted the pull requests to the health-data-standards gem, quality-measure-engine gem and popHealth.