DOCSP-36972: Copy data from multiple sources (#199)

* DOCSP-36972: Copy data from multiple sources

* edits

* edits

* admonition

* JV feedback

* fix

* CN feedback

(cherry picked from commit 8d6c63d)

Author: norareidy

source/includes/usage-examples/copy/multisource.json

@@ -0,0 +1,12 @@
+{
+    "_id": { "_id": 1, "copyingData": true },
+    "operationType": "insert",
+    "documentKey": { "_id": 1 },
+    "fullDocument": {
+      "_id": 1,
+      "item_name": "lipstick",
+      "department": "cosmetics",
+      "quantity": 45
+    },
+    "ns": { "db": "shopping", "coll": "products" }
+  }

source/includes/usage-examples/copy/multisource.properties

@@ -0,0 +1,5 @@
+connector.class=com.mongodb.kafka.connect.MongoSourceConnector
+connection.uri=<your production MongoDB connection uri>
+database=shopping
+startup.mode=copy_existing
+startup.mode.copy.existing.namespace.regex=^shopping\.(customers|products)$

source/source-connector/usage-examples/copy-existing-data.txt

@@ -4,11 +4,30 @@
 Copy Existing Data
 ==================
 
-This usage example demonstrates how to copy data from a MongoDB collection to an
+.. facet::
+   :name: genre
+   :values: reference
+
+.. meta:: 
+   :keywords: code example, copy, filter, configuration setting
+
+.. contents:: On this page
+   :local:
+   :backlinks: none
+   :depth: 2
+   :class: singlecol
+
+These usage examples demonstrate how to copy data from MongoDB to an
 {+kafka+} topic using the {+source-connector+}.
 
-Example
--------
+Examples
+--------
+
+The following examples show how to configure your source connector to
+copy existing data from a single collection or from multiple collections.
+
+Copy and Filter Collection Data
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Suppose you want to copy a MongoDB collection to {+kafka+} and filter some data.
 
@@ -51,7 +70,7 @@ The ``customers`` collection contains the following documents:
 .. _source-usage-example-copy-existing-data-copy-data:
 
 Copy Data
-~~~~~~~~~
+`````````
 
 Copy the contents of the ``customers`` collection of the ``shopping`` database by 
 specifying the following configuration options in your source connector:
@@ -78,7 +97,7 @@ To learn more about the ``startup.mode`` option, see
 .. _source-usage-example-copy-existing-data-mask-data:
 
 Filter Data
-~~~~~~~~~~~
+```````````
 
 You can filter data by specifying an aggregation pipeline in the 
 ``startup.mode.copy.existing.pipeline`` option of your source connector configuration. The
@@ -97,9 +116,10 @@ To learn more about aggregation pipelines, see the following resources:
 - :ref:`<source-usage-example-custom-pipeline>` Usage Example
 - :manual:`Aggregation </aggregation>` in the MongoDB manual.
 
+.. _source-usage-example-copy-existing-data-config:
 
 Specify the Configuration
-~~~~~~~~~~~~~~~~~~~~~~~~~
+`````````````````````````
 
 Your final source connector configuration to copy the ``customers`` collection should
 look like this:
@@ -116,10 +136,47 @@ in the ``shopping.customers`` {+kafka+} topic:
 .. literalinclude:: /includes/usage-examples/copy/payload.json
     :language: json
     :copyable: false
-    :emphasize-lines: 6,7
 
 .. note:: Write the Data in your Topic into a Collection
 
    Use a change data capture handler to convert change event documents in an
    {+kafka+} topic into MongoDB write operations. To learn more, see the
    :ref:`Change Data Capture Handlers <sink-fundamentals-cdc-handler>` guide.
+
+Copy Data From Multiple Sources
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Suppose you want to copy data from another collection in the ``shopping``
+database named ``products``, which contains the following document:
+
+.. code-block:: json
+   :copyable: false
+
+   {
+     "_id": 1,
+     "item_name": "lipstick",
+     "department": "cosmetics",
+     "quantity": 45
+   }
+
+You can copy from both the ``customers`` and ``products`` collections
+by using the ``startup.mode.copy.existing.namespace.regex`` configuration
+setting, as shown in the following code:
+
+.. literalinclude:: /includes/usage-examples/copy/multisource.properties
+    :language: properties
+    :emphasize-lines: 5
+
+In addition to the change event document in the ``shopping.customers`` {+kafka+} topic,
+described in the :ref:`preceding section <source-usage-example-copy-existing-data-config>`,
+you can see the following document in the ``shopping.products`` topic:
+
+.. literalinclude:: /includes/usage-examples/copy/multisource.json
+    :language: json
+    :copyable: false
+
+.. tip::
+
+   To learn more about the ``startup.mode.copy.existing.namespace.regex`` setting,
+   see the :ref:`Settings table <source-configuration-startup-table-start>` in
+   the Startup Properties guide.