DOCSP-8628: Document new 'hello' command

Author: npentrel

config/redirects

@@ -1784,3 +1784,11 @@ raw: /manual/core/wildcard -> ${base}/manual/core/index-wildcard/
 [v3.4-v4.0]: /${version}/reference/mongodb-defaults -> ${base}/${version}/reference/
 
 [v3.6-*]: /${version}/reference/command/clean -> ${base}/${version}/reference/command/nav-administration/
+
+#
+# Redirects for 5.0 and greater (if pages are removed in 4.4 that used to exist in earlier versions)
+#
+
+[v5.0-*]: /${version}/reference/command/isMaster -> ${base}/${version}/reference/command/hello
+[v5.0-*]: /${version}/reference/method/db.isMaster -> ${base}/${version}/reference/method/db.hello
+

source/core/replica-set-hidden-member.txt

@@ -19,7 +19,7 @@ data set but is **invisible** to client applications. Hidden members
 are good for workloads with different usage patterns from the other
 members in the :term:`replica set`. Hidden members must always be
 :ref:`priority 0 members <replica-set-secondary-only-members>` and
-so **cannot become primary**. The :method:`db.isMaster()` method does not
+so **cannot become primary**. The :method:`db.hello()` method does not
 display hidden members. Hidden members, however, **may vote** in
 :ref:`elections <replica-set-elections>`.
 

source/core/sharded-cluster-query-router.txt

@@ -205,15 +205,15 @@ Confirm Connection to ``mongos`` Instances
 ------------------------------------------
 
 To detect if the MongoDB instance that your client is connected
-to is :binary:`~bin.mongos`, use the :dbcommand:`isMaster` command. When a
-client connects to a :binary:`~bin.mongos`, :dbcommand:`isMaster` returns
+to is :binary:`~bin.mongos`, use the :dbcommand:`hello` command. When a
+client connects to a :binary:`~bin.mongos`, :dbcommand:`hello` returns
 a document with a ``msg`` field that holds the string
 ``isdbgrid``. For example:
 
 .. code-block:: javascript
 
    {
-      "ismaster" : true,
+      "isWritablePrimary" : true,
       "msg" : "isdbgrid",
       "maxBsonObjectSize" : 16777216,
       "ok" : 1,

source/includes/extracts-server-status-projection-base.yaml

@@ -27,13 +27,13 @@ content: |
 
       - :serverstatus:`metrics.commands.update.arrayFilters`
 
-      - :serverstatus:`metrics.commands.findAndModify.arrayFilters`     
+      - :serverstatus:`metrics.commands.findAndModify.arrayFilters`
 
     - Added new metric to track number of times ``newlyAdded`` fields
       were automatically removed:
 
       - :serverstatus:`metrics.repl.reconfig.numAutoReconfigsForRemovalOfNewlyAddedFields`
-      
+
     - Replaced :serverstatus:`opReadConcernCounters` with
       :serverstatus:`readConcernCounters` to track use of read concern
       levels specified by query operations
@@ -56,6 +56,10 @@ content: |
 
       - :serverstatus:`metrics.cursor.totalOpened`
 
+    - Added new metric to track hello commands:
+
+      - :serverstatus:`connections.exhaustHello`
+
   - Starting in MongoDB 4.4, {{operationName}}:
 
     - Added new metrics to track write concern failures caused

source/includes/extracts-transactions.yaml

@@ -115,7 +115,7 @@ content: |
 ref: transactions-operations-restrictions-info
 content: |
 
-   Informational commands, such as :dbcommand:`isMaster`,
+   Informational commands, such as :dbcommand:`hello`,
    :dbcommand:`buildInfo`, :dbcommand:`connectionStatus` (and their
    helper methods) are allowed in transactions; however, they cannot be
    the first operation in the transaction.

source/includes/fact-bulkwrite-operation-batches.rst

@@ -1,7 +1,7 @@
 The number of operations in each group cannot exceed the value of
 the :limit:`maxWriteBatchSize <Write Command Batch Limit Size>` of
 the database. As of MongoDB 3.6, this value is ``100,000``.
-This value is shown in the :data:`isMaster.maxWriteBatchSize` field.
+This value is shown in the :data:`hello.maxWriteBatchSize` field.
 
 This limit prevents issues with oversized error messages. If a group
 exceeds this :limit:`limit <Write Command Batch Limit Size>`,

source/reference/command.txt

@@ -335,9 +335,9 @@ Replication Commands
 
      - Internal command that applies :term:`oplog` entries to the current data set.
 
-   * - :dbcommand:`isMaster`
+   * - :dbcommand:`hello`
 
-     - Displays information about this member's role in the replica set, including whether it is the master.
+     - Displays information about this member's role in the replica set, including whether it is the primary.
 
    * - :dbcommand:`replSetAbortPrimaryCatchUp`