DataStructure about openki

[1u]

http://stackoverflow.com/questions/8901977/mongodb-nested-array-search
http://stackoverflow.com/questions/6179871/mongodb-wildcard-in-the-key-of-a-query
https://groups.google.com/forum/#!topic/mongodb-user/MrANONUL2Fg

$where clause: not recommended

[lazymazy]

felix: aggregation in meteor
http://stackoverflow.com/questions/18520567/average-aggregation-queries-in-meteor

https://github.com/awatson1978/meteor-cookbook/blob/master/cookbook/collection-aggregation.md
https://github.com/awatson1978/meteor-cookbook/blob/master/cookbook/aggregation.md
https://github.com/awatson1978/meteor-cookbook/blob/master/cookbook/collections.md

[1u]

TestCourses2
'roles': ['team', 'participant', 'host']
'subscribed': [
{'user':'FeeLing', 'roles': ['team', 'participant']},
{'user':'Chrosle', 'roles': ['participant']},
{'user':'greg', 'roles': ['host'], 'locations': ['ABC', 'ABD']}, // ?
]
'locations': [ // ?
{
]