DOCS-649 migrate metadata wiki page to manual

Author: Bob Grabar

draft/reference/metadata.txt

@@ -0,0 +1,91 @@
+========
+Metadata
+========
+
+.. default-domain:: mongodb
+
+.. index:: metadata
+.. _metadata-storage:
+
+Metadata Storage
+----------------
+
+MongoDB stores metadata in :term:`collections <collection>` and in
+:term:`documents <document>`. MongoDB stores metadata as follows:
+
+- System metadata for a given :term:`database` is stored in collections
+  that use the ``system`` :term:`namespace`. For a list of ``system``
+  collections and where they are found, see
+  :ref:`metadata-system-collections`
+
+- Replication metadata is stored in the ``local`` database, which exists
+  only on members of :term:`replica sets <replica set>`. For
+  descriptions of the collections that store replication metadata, see
+  :ref:`replica-set-local-database`.
+
+- Metadata on document structure is stored in the :term:`BSON` format
+  within the document itself.
+
+.. index:: collection; internal collections
+.. index:: internal collections
+.. _metadata-system-collections:
+
+Internal Collections
+--------------------
+
+MongoDB creates several internal collections to use for system,
+replication, and sharding metadata. They are described in the following
+sections in this manual:
+
+- :ref:`metadata-system-collections`
+
+- :ref:`replica-set-local-database`
+
+- :ref:`sharding-internals-config-database`
+
+.. index:: collection; system
+.. index:: system; collections
+.. index:: system; namespace
+.. index:: namespace; system
+.. _metadata-system-collections:
+
+System Collections
+------------------
+
+MongoDB stores system information in collections that use the
+``system.*`` :term:`namespace`. This namespace is reserved for system
+information and should not be used for other collections.
+
+System collections include collections that are stored directly in the database as well as
+collections that are stored in the ``local`` database on a :term:`replica set` member.
+
+System collections include these collections stored directly in the database:
+
+.. data:: <database>.system.namespaces
+
+   The :data:`<database>.system.namespaces` collection contains
+   information about all of the database’s collections. Additional
+   namespace metadata exists in the ``database.ns`` files and is opaque.
+
+.. data:: <database>.system.indexes
+
+   The :data:`<database>.system.indexes` collection lists all the
+   indexes in the database. You add and remove data from this collection
+   via the :method:`ensureIndex() <db.collection.ensureIndex()>` and
+   :method:`dropIndex() <db.collection.dropIndex()>`
+
+.. data:: <database>.system.profile
+
+   The :data:`<database>.system.profile` collection stores database
+   profiling information. For information on profiling, see :ref:`database-profiling`.
+
+.. data:: <database>.system.users
+
+   The :data:`<database>.system.users` collection stores credentials for
+   users who have access to the database. For more information on this collection, see
+   :ref:`security-authentication`.
+
+System collections also include collections that are stored in the
+``local`` database on replica set members, when replication is enabled.
+For descriptions of system collections stored in the ``local`` database,
+see :ref:`replica-set-local-database`.

source/core/replication-internals.txt

@@ -10,10 +10,13 @@ normal operation or application development but may be useful for
 troubleshooting and for further understanding MongoDB's behavior and approach.
 
 .. index:: replica set; local database
+.. index:: local database
+.. index:: database; local
+.. index:: namespace; local
 .. _replica-set-local-database:
 
-The ``local`` Database
-----------------------
+Local Database
+--------------
 
 The ``local`` database exists on every :program:`mongod` instance and
 stores replication data specific to that instance. The ``local``

source/core/sharding-internals.txt

@@ -513,8 +513,6 @@ When the ``_secondaryThrottle`` is ``true`` for :dbcommand:`moveChunk`
 or the :term:`balancer`, MongoDB ensure that *one* :term:`secondary`
 member has replicated changes before allowing new chunk migrations.
 
-.. _sharding-internals-config-database:
-
 Detect Connections to :program:`mongos` Instances
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -536,6 +534,10 @@ a document with a ``msg`` field that holds the string
 If the application is instead connected to a :program:`mongod`, the
 returned document does not include the ``isdbgrid`` string.
 
+.. index:: config database
+.. index:: database, config
+.. _sharding-internals-config-database:
+
 Config Database
 ---------------