Any way to create a group by query in mongo? then make it add a column together?

[wozzzzz]

running PHP with mongo and apache on windows 8. I have a database that lists each session a computer has on the internet, it has a MAC address and the number of bytes the computer has downloaded.

the MAC address's of computers appear more than once with the bytes in the other column.

how would I create a grouped query to list all the MAC addresses in the database and add all the bytes column up to get a total for each MAC address?

MAC             BYTES

a3:e4:23      35645

f5:13:d2        1354185

63:a1:c1      8135181

a3:e4:23      67246

f5:13:d2      6848624

a3:e4:23     3542494

then the output when printing the list will look like this with the bytes columns added together and mac's grouped

MAC             BYTES

a3:e4:23      3645385

f5:13:d2        8202809

63:a1:c1      8135181

[Asya Kamsky]

Yep, that's what aggregation framework aka pipeline does.  Look up aggregate $group and the $sum function.  The _id should be what you are grouping on.

db.collection.aggregate({$group:{_id:"$a", sums:{$sum:"$counts"}}})

will group by field/column a ($ means contents of a otherwise it would be a literal string) adding all values of field counts for each distinct value of a.

Asya

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[wozzzzz]

using the aggregate function I get "Call to undefined method MongoCollection::aggregate()"

im running driver 1.5.1 in php with apache on windows.

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[Asya Kamsky]

Without seeing your code it would be hard for me to guess where the problem is.

There are a few examples here:  http://www.php.net/manual/en/mongocollection.aggregate.php  Does your code look similar to that?

If so, maybe post it here and someone is likely to spot what the issue is.

Asya

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[wozzzzz]

tried that with a very simple query to begin with, but aggregate function is undefined. maybe an older version of mongo or something?? where you define the connection mongoclient(), I have to use mongo() as mongoclient doesn't work.

anyway I got it working using arrays and a simple query and added the arrays up.

[Asya Kamsky]

Seems unlikely to be old version - 1.5.1 was released in May and aggregate helper has been around for almost two years.

You should be using MongoClient class rather than Mongo - MongoClient has been available since version 1.3.0 - same version that added aggregate, I think - are you sure that you're on 1.5.1?

Asya

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