Aggregation framework slower than group()?

[Nicolas Grilly]

Hello list,

I'm testing MongoDB 2.1.0 in order to evaluate the performance of the new aggregation framework. I'm wondering why it's 2x slower in my use case.

Here is the code I used before version 2.1.0 (using Python and pymongo):

        db.customers.group(

            {'segment': True},

            None,

            {'count': 0},

            "function (obj, prev) { prev.count ++; }"

        )

Here is the same computation using the new aggregation framework:

        db.command('aggregate', 'customers', pipeline=[

            {'$group' : {

                '_id': '$segment',

                'count': {'$sum': 1}

            }}

        ])

On my computer and with my dataset, the first version runs in ~1 s, the second version in ~2.5 s. Is it expected or am I doing something wrong?

Cheers,

Nicolas

[Scott Hernandez]

The framework is still being developed. Providing feedback with sample data, your pipelines and your experiences is good but there are still lots of optimizations to be made.

See the other questions/responses for a list of some of the optimations coming.

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[Nicolas Grilly]

Thanks for your answer Scott. I'll redo my tests in a few weeks with the next release.

[Scott Hernandez]

The first official release will be the 2.2.0 (stable) release.
Currently this is a developer preview or unstable development release
depending on who you.

Here is a little background on versioning and release numbers.
http://www.mongodb.org/display/DOCSKR/Version+Numbers

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