DOCS-1208 agg command overview/xref

bin/htaccess.yaml

@@ -1783,4 +1783,11 @@ code: 301
 outputs:
   - 'after-v2.2'
   - 'manual'
+---
+redirect-path: '/reference/aggregation-reference-overview'
+url-base: '/aggregation'
+type: 'redirect'
+code: 303
+outputs:
+  - 'v2.2'
 ...

source/aggregation.txt

@@ -24,3 +24,4 @@ aggregation tools for MongoDB here:
    reference/sql-aggregation-comparison
    core/map-reduce
    reference/simple-aggregation
+   reference/aggregation-commands-overview

source/includes/table-aggregation-xref.yaml

@@ -0,0 +1,130 @@
+# table structure. all content symbolic.
+section: layout
+header: [ meta.header4, meta.header3, meta.header2, meta.header1]
+rows: 
+  - 1: [ meta.row1, content.agg1, content.mr1, content.grp1]
+  - 2: [ meta.row2, content.agg2, content.mr2, content.grp2]
+  - 3: [ meta.row3, content.agg3, content.mr3, content.grp3]
+  - 4: [ meta.row4, content.agg4, content.mr4, content.grp4]
+  - 5: [ meta.row5, content.agg5, content.mr5, content.grp5]
+  - 6: [ meta.row6, content.blank, content.v8, content.v8]
+  - 7: [ meta.row7, content.agg7, content.mr7, content.grp7]
+---
+# table metadata, as meta.<key>
+section: meta
+header1: :dbcommand:`group`
+header2: :dbcommand:`mapReduce`
+header3: :dbcommand:`aggregate`
+header4: " "
+row1: "**Description**"
+row2: "**Key Features**"
+row3: "**Flexibility**"
+row4: "**Output Results**"
+row5: "**Sharding**"
+row6: "**Notes**"
+row7: "**More Information**"
+---
+# table content, as content.<key>
+section: content
+blank: " "
+v8: |
+    Prior to 2.4, JavaScript code executed in a single thread.
+grp1: |
+   Provides grouping functionality.
+
+   Is slower than the :dbcommand:`aggregate` command and has less
+   functionality than the :dbcommand:`mapReduce` command.
+
+grp2: |
+      Can either group by existing fields or with a custom ``keyf``
+      JavaScript function, can group by calculated fields.
+
+      See :dbcommand:`group` for information and example using the 
+      ``keyf`` function.
+grp3: |
+      Custom ``reduce`` and ``finalize`` JavaScript functions offer
+      flexibility to grouping logic.
+
+      See :dbcommand:`group` for details and restrictions on these
+      functions.
+
+grp4: |
+      Returns results inline as an array of grouped items.
+
+      The result set must fit within the :ref:`maximum BSON document
+      size limit <limit-bson-document-size>`.
+
+      .. versionchanged:: 2.2
+         The returned array can contain at most 20,000 elements; i.e.
+         at most 20,000 unique groupings. Previous versions had a limit
+         of 10,000 elements.
+grp5: |
+      Does **not** support sharded collection.
+grp7: |
+      See :dbcommand:`group`.
+mr1: |
+     Implements the Map-Reduce aggregation for processing large data sets.
+mr2: |
+     In addition to grouping operations, can perform complex
+     aggregation tasks as well as perform incremental aggregation on
+     continuously growing datasets.
+
+     See :doc:`/tutorial/map-reduce-examples/` and
+     :doc:`/tutorial/perform-incremental-map-reduce/`.
+
+mr3: |
+     Custom ``map``, ``reduce`` and ``finalize`` JavaScript
+     functions offer flexibility to aggregation logic.
+
+     See :dbcommand:`mapReduce` for details and restrictions
+     on the functions.
+mr4: |
+     Returns results in various options (inline, new collection, merge,
+     replace, reduce). See :dbcommand:`mapReduce` for details on the
+     output options.
+
+     .. versionchanged:: 2.2
+        Provides much better support for sharded map-reduce output than
+        previous versions.
+mr5: Supports non-sharded and sharded input collections.
+mr7: |
+     See :doc:`/core/map-reduce` and :dbcommand:`mapReduce`.
+agg1: |
+      .. versionadded:: 2.2
+
+      Designed with specific goals of improving performance and
+      usability for aggregation tasks.
+
+      Uses a "pipeline" approach where objects are transformed as they
+      pass through a series of pipeline operators such as
+      :pipeline:`$group`,  :pipeline:`$match`, and :pipeline:`$sort`.
+
+      See :doc:`/reference/aggregation` for more information on the
+      pipeline operators.
+agg2: |
+      Pipeline operators can be repeated as needed.
+
+      Pipeline operators need not produce one output document for every
+      input document.
+
+      Can also generate new documents or filter out documents.
+agg3: |
+      Limited to the operators and expressions supported by the
+      Aggregation Framework.
+
+      However, can add computed fields, create new virtual sub-objects,
+      and extract sub-fields into the top-level of results by using the
+      :pipeline:`$project` pipeline operator.
+
+      See :pipeline:`$project` for more information as well as 
+      :doc:`/reference/aggregation` for more information on all the
+      available pipeline operators.
+agg4: |
+      Returns results inline.
+
+      The result is subject to the :ref:`BSON Document size
+      <limit-bson-document-size>` limit.
+agg5: Supports non-sharded and sharded input collections.
+agg7: |
+      See :doc:`/core/aggregation` and :dbcommand:`aggregate`.
+...

source/reference/aggregation-commands-overview.txt

@@ -0,0 +1,13 @@
+===================================
+Aggregation Commands Overview Chart
+===================================
+
+.. default-domain:: mongodb
+
+MongoDB provides the :dbcommand:`aggregate`, :dbcommand:`mapReduce`, and
+:dbcommand:`group` commands to perform aggregations.
+
+The following table provides a brief overview of the features of the
+commands.
+
+.. include:: /includes/table-aggregation-xref.rst