DOCS-14020 documents listDatabase output changes for 5.0

Author: jmd-mongo

source/reference/command/listDatabases.txt

@@ -101,37 +101,14 @@ Definition
 
           .. versionadded:: 4.4
 
-
-Output
-------
-
-:dbcommand:`listDatabases` returns a document that contains:
-
-- A field named ``databases`` whose value is an array of documents, one
-  document for each database. Each document contains:
-
-  - A ``name`` field with the database name.
-
-  - A ``sizeOnDisk`` field with the total size of the database files on
-    disk in bytes.
-
-  - An ``empty`` field specifying whether the database has any data.
-
-  - For sharded clusters, a ``shards`` field that includes the shard
-    and the size in bytes of the database on disk for each shard.
-
-- A field named ``totalSize`` whose value is the sum of all the
-  ``sizeOnDisk`` fields in bytes.
-
 .. _listDatabases-behavior:
 
 Behavior
 --------
 
 When :doc:`authentication </core/authentication>` is enabled:
 
-.. note:: show dbs
-
+.. note::
 
    For :binary:`~bin.mongo` shell version 4.0.6+ connected to earlier
    versions of MongoDB deployment (e.g. 3.6.10), 
@@ -238,6 +215,7 @@ The following is an example of a :dbcommand:`listDatabases` result:
          }
       ],
       "totalSize" : 251658240,
+      "totalSizeMb" : 251,
       "ok" : 1
    }
 
@@ -290,6 +268,8 @@ name matches the specified :query:`regular expression <$regex>`:
 
    db.adminCommand( { listDatabases: 1, filter: { "name": /^rep/ } } )
 
+.. _listDatabases-sharded-clusters:
+
 Sharded Clusters
 ~~~~~~~~~~~~~~~~
 
@@ -345,9 +325,66 @@ For example:
      "ok" : 1
    }
 
-.. seealso::
-
+.. seealso:: 
+ 
    :doc:`/tutorial/use-database-commands`.
 
+Output
+------
+
+.. data:: listDatabases.databases
+
+   *Type: Array*
+
+   Array of documents, each containing information on a single
+   database.
+   
+.. data:: listDatabases.databases.name
+ 
+   *Type: String*
+
+   Name of the database.
+
+.. data:: listDatabases.databases.sizeOnDisk
+
+   *Type: Integer*
+
+   Total size of the database files on disk, expressed in bytes.
+
+.. data:: listDatabases.databases.empty
+
+   *Type: Boolean*
+   
+   Specifies whether the database is empty.
+   
+.. data:: listDatabases.databases.shards
+
+   *Type: Document*
+
+   Each element in the ``shards`` document consists of a field whose key 
+   gives the name of a collection on that shard, and whose value 
+   represents the collection's size in bytes.
+
+   ``shards`` only appears in the output if ``nameOnly: false``.
+
+   See :ref:`Sharded Clusters <listDatabases-sharded-clusters>`
+   for details.
+
+.. data:: listDatabases.totalSize
+
+   *Type: Integer*
+
+   Sum of all the ``sizeOnDisk`` fields in bytes.
+
+.. data:: listDatabases.totalSizeMb
+
+   *Type: Integer*
+
+   Sum of all the ``sizeOnDisk`` fields, expressed in megabytes.
+
+.. data:: listDatabases.ok
+
+   *Type: Integer*
 
-.. |checkmark| unicode:: U+2713
+   Return value for the command. A value of ``1`` indicates
+   success.

source/release-notes/5.0-compatibility.txt

@@ -131,6 +131,66 @@ operand expression ( ``{ }`` ):
 An empty update results in no changes and no :term:`oplog` entry is
 created (meaning that the operation is a no-op).
 
+``listDatabases`` Output Changes
+--------------------------------
+
+Starting in MongoDB 5.0, output from the :dbcommand:`listDatabases` 
+command running against a :binary:`~bin.mongod` is more consistent with 
+output from :dbcommand:`listDatabases` running against a 
+:binary:`~bin.mongos`.
+
+The following table shows the differences in data types for
+:dbcommand:`listDatabases` output fields between MongoDB 5.0 and earlier
+versions. Only fields which differ between 5.0 and earlier versions are 
+listed. 
+
+.. list-table::
+   :header-rows: 1
+   :widths: 25 25 25 25
+   
+   * - Field
+   
+     - Type in MongoDB 5.0 
+
+     - Type in MongoDB 4.4 and earlier (``mongod``)
+
+     - Type in MongoDB 4.4 and earlier (``mongos``)
+   
+   * - ``sizeOnDisk``
+   
+     - integer
+    
+     - double
+
+     - integer
+   
+   * - ``totalSize``
+  
+     - integer
+   
+     - double
+
+     - integer
+  
+   * - ``totalSizeMb``
+ 
+     - integer
+
+     - not present (see below)
+
+     - integer  
+
+The output from :dbcommand:`listDatabases` now includes the 
+``totalSizeMb`` field when run against either a :binary:`~bin.mongos` or 
+a :binary:`~bin.mongod`. In MongoDB 4.4 and earlier, ``totalSizeMb`` 
+only appears when run against :binary:`~bin.mongos`. ``totalSizeMb`` is 
+the sum of the ``sizeOnDisk`` fields, expressed in megabytes.  
+
+When run against :binary:`~bin.mongos`, the ``shards`` field in the
+:dbcommand:`listDatabases` output contains a field-value pair for each
+collection on a particular shard. Size values in the ``shards`` field 
+are expressed as integers.
+
 General Changes
 ---------------