How to do distinct using aggregation framework

[songhe yang]

RT

I didn't find the distinct operator in aggregation framework in
pipeline operators, so how to do distinct using aggregation framework?

[Scott Hernandez]

You use $group. Are you just trying to get the number or the list of
distinct values?

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[Scott Hernandez]

You use $group. Are you just trying to get the number or the list of
distinct values?

On Sat, Feb 11, 2012 at 7:38 AM, songhe yang <songh...@gmail.com> wrote:

[songhe yang]

I want to get the list of distinct values.

One more question:

Why not provide the distinct operator in pipeline operator?

[Scott Hernandez]

It is easy to do like so:

db.runCommand({
"aggregate" : "people",
"pipeline" : [
{
"$group" : {
"_id" : "$name"
}
}]})

This creates a unique list of the name field.

Not sure distinct makes sense as a pipeline operator. Feel free to add
a request: http://jira.mongodb.org/

[SreenathV]

Distinct can be achieved using pipes in Aggregate framework...Sample code snippet athttp://www.techiesinfo.com/code-snippet analysing clickstream