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Asked: 2026-06-01T15:00:44+00:00

Mongodb Database: {thread: abc, message: hjhjh, Date: (2010,4,5,0,0,0)} {thread: abc, message: hjhjh, Date: (2009,3,5,0,0,0)}

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Mongodb Database:

{"thread": "abc", "message": "hjhjh", "Date": (2010,4,5,0,0,0)}
{"thread": "abc", "message": "hjhjh",  "Date": (2009,3,5,0,0,0)}
{"thread": "efg", "message": "hjhjh",  "Date": (2010,3,7,0,0,0)}
{"thread": "efg", "message": "hjhjh",  "Date": (2011,4,5,0,0,0)}

How can I Map-Reduce or aggregate on the above data to generate an output as:

{"thread": "abc", "messages_per_month": 5}
{"thread": "efg", "messages_per_month": 4}

I am trying to write some code but its difficult to average on unsorted dates. Are there any built in functions averaging on time to do this?

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1 Answer

  1. Editorial Team

    You could do min/max on the dates like described here for numbers and just add a counter for the messages. The result would be a list of threads with the number of messages and min/max date. From the dates you can calculate the number of months which you can then use to average on the number of messages.

    Edit: updated link with link to archived version

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