docs/source/reference/command/mapReduce.txt at 499ae6158885733df5ae17cb05529d1ce0a9d356 · mongodb/docs · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
=========
mapReduce
=========

.. default-domain:: mongodb

.. dbcommand:: mapReduce

   The :dbcommand:`mapReduce` command allows you to run
   :term:`map-reduce` aggregation operations over a collection. The
   :dbcommand:`mapReduce` command has the following prototype
   form:

   .. code-block:: javascript

      db.runCommand(
                     {
                       mapReduce: <collection>,
                       map: <function>,
                       reduce: <function>,
                       out: <collection>,
                       query: <document>,
                       sort: <document>,
                       limit: <number>,
                       finalize: <function>,
                       scope: <document>,
                       jsMode: <boolean>,
                       verbose: <boolean>
                     }
                   )

   Pass the name of the collection to the ``mapReduce`` command
   (i.e. ``<collection>``) to use as the source documents to perform
   the map reduce operation. The command also accepts the following
   parameters:

   .. include:: /includes/parameters-map-reduce.rst

   Consider the following prototype map:dbcommand:`mapReduce`
   operation:

   .. code-block:: javascript

      var mapFunction = function() { ... };
      var reduceFunction = function(key, values) { ... };

      db.runCommand(
                     {
                       mapReduce: 'orders',
                       map: mapFunction,
                       reduce: reduceFunction,
                       out: { merge: 'map_reduce_results' },
                       query: { ord_date: { $gt: new Date('01/01/2012') } }
                     }
                   )

   In the :program:`mongo`, the :method:`db.collection.mapReduce()`
   method is a wrapper around the :dbcommand:`mapReduce` command. The
   following examples use the :method:`db.collection.mapReduce()`:

   .. include:: /includes/examples-map-reduce.rst
      :start-after: map-reduce-document-prototype-begin
      :end-before: map-reduce-document-prototype-end

   - .. include:: /includes/examples-map-reduce.rst
        :start-after: map-reduce-sum-price-begin
        :end-before: map-reduce-sum-price-end

   - .. include:: /includes/examples-map-reduce.rst
        :start-after: map-reduce-counts-begin
        :end-before: map-reduce-counts-end

   For more information and examples, see the :doc:`Map-Reduce
   </applications/map-reduce>` page.

   .. seealso::

      - :term:`map-reduce` and :method:`db.collection.mapReduce()`

      - :doc:`/applications/aggregation`

   .. slave-ok