edits

Author: norareidy

source/databases-collections.txt

@@ -187,10 +187,8 @@ The following example deletes the ``test_collection`` collection:
 Configure Read and Write Operations
 -----------------------------------
 
-You can control how the library routes read operations by setting a **read preference**.
-You can also control options for how the library waits for acknowledgment of
-read and write operations on a replica set by setting a **read concern** and a
-**write concern**.
+You can control how read and write operations run on replica sets
+by specifying a read preference, read concern, and write concern.
 
 By default, databases inherit read and write settings from the ``MongoDB\Client``
 instance. Collections inherit these settings from the ``MongoDB\Client`` or

source/includes/read-write-pref.php

@@ -10,7 +10,7 @@
 $clientOptions = [
     'readPreference' => 'secondary',
     'readConcernLevel' => 'local',
-    'w' => 'majority',
+    'w' => '2',
 ];
 
 $client = new Client('mongodb://localhost:27017', $clientOptions);
@@ -23,7 +23,7 @@
 
 // start-session-settings
 $sessionOptions = [
-    'readPreference' => new ReadPreference(ReadPreference::RP_SECONDARY),
+    'readPreference' => new ReadPreference(ReadPreference::PRIMARY_PREFERRED),
     'readConcern' => new ReadConcern(ReadConcern::LOCAL),
     'writeConcern' => new WriteConcern(WriteConcern::MAJORITY),
 ];
@@ -33,9 +33,9 @@
 
 // start-transaction-settings
 $transactionOptions = [
-    'readPreference' => new ReadPreference(ReadPreference::RP_PRIMARY),
-    'readConcern' => new ReadConcern(ReadConcern::AVAILABLE),
-    'writeConcern' => new WriteConcern(WriteConcern::MAJORITY),
+    'readPreference' => new ReadPreference(ReadPreference::PRIMARY),
+    'readConcern' => new ReadConcern(ReadConcern::MAJORITY),
+    'writeConcern' => new WriteConcern(1),
 ];
 
 // Start the transaction
@@ -44,8 +44,8 @@
 
 // Sets read and write settings for the "test_database" database
 // start-database-settings
-$readPreference = new ReadPreference(ReadPreference::RP_PRIMARY_PREFERRED);
-$readConcern = new ReadConcern(ReadConcern::LOCAL);
+$readPreference = new ReadPreference(ReadPreference::PRIMARY_PREFERRED);
+$readConcern = new ReadConcern(ReadConcern::AVAILABLE);
 $writeConcern = new WriteConcern(WriteConcern::MAJORITY);
 
 $db = $client->selectDatabase('test_database', [
@@ -57,9 +57,9 @@
 
 // Sets read and write settings for the "test_collection" collection
 // start-collection-settings
-$readPreference = new ReadPreference(ReadPreference::RP_PRIMARY);
+$readPreference = new ReadPreference(ReadPreference::SECONDARY_PREFERRED);
 $readConcern = new ReadConcern(ReadConcern::AVAILABLE);
-$writeConcern = new WriteConcern(WriteConcern::MAJORITY);
+$writeConcern = new WriteConcern(0);
 
 $collection = $client->selectCollection('test_database', 'test_collection', [
     'readPreference' => $readPreference,

source/read-write-pref.txt

@@ -45,6 +45,11 @@ in your replica sets.
 Configure Read and Write Operations
 -----------------------------------
 
+You can control how the library routes read operations by setting a **read preference**.
+You can also control options for how the library waits for acknowledgment of
+read and write operations on a replica set by setting a **read concern** and a
+**write concern**.
+
 This section shows how to configure the read preference, read concern, and write
 concern at various levels by passing an options array parameter to the following
 methods:
@@ -84,9 +89,17 @@ In the options parameter, specify the following values:
 Client Configuration Example
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The following example shows how to set the read preference, read concern, and
+This example shows how to set the read preference, read concern, and
 write concern of a ``MongoDB\Client`` instance by passing an array to
-the constructor:
+the constructor. The code configures the following settings:
+
+- ``secondary`` read preference: Read operations retrieve data from 
+  secondary replica set members
+- ``local`` read concern: Read operations return the instance's most recent data 
+  without guaranteeing that the data has been written to a majority of the replica
+  set members
+- ``2`` write concern: The primary and one secondary replica set member
+  must acknowledge the write operation
 
 .. literalinclude:: /includes/read-write-pref.php
     :language: php
@@ -108,9 +121,18 @@ URI, which is passed as a parameter to the ``MongoDB\Client`` constructor:
 Session Configuration Example
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The following example shows how to set the read preference, read concern, and
+This example shows how to set the read preference, read concern, and
 write concern of a session by passing an array to the ``startSession()``
-method:
+method. The code configures the following settings:
+
+- ``PRIMARY_PREFERRED`` read preference: Read operations retrieve data from 
+  the primary replica set member, or secondary members if the primary is unavailable
+- ``LOCAL`` read concern: Read operations return the instance's most recent data 
+  without guaranteeing that the data has been written to a majority of the replica
+  set members
+- ``MAJORITY`` write concern: The majority of all replica set members
+  must acknowledge the write operation
+
 
 .. literalinclude:: /includes/read-write-pref.php
     :language: php
@@ -123,9 +145,16 @@ method:
 Transaction Configuration Example
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The following example shows how to set the read preference, read concern, and
+This example shows how to set the read preference, read concern, and
 write concern of a transaction by passing an array to the ``startTransaction()``
-method:
+method. The code configures the following settings:
+
+- ``PRIMARY`` read preference: Read operations retrieve data from 
+  the primary replica set member
+- ``MAJORITY`` read concern: Read operations return the instance's most recent data 
+  that has been written to a majority of replica set members
+- ``1`` write concern: The primary replica set member must acknowledge the
+  write operation
 
 .. literalinclude:: /includes/read-write-pref.php
     :language: php
@@ -138,9 +167,17 @@ method:
 Database Configuration Example
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The following example shows how to set the read preference, read concern, and
+This example shows how to set the read preference, read concern, and
 write concern of a database called ``test_database`` by passing an options
-array to the ``selectDatabase()`` method:
+array to the ``selectDatabase()`` method. The code configures the following settings:
+
+- ``PRIMARY_PREFERRED`` read preference: Read operations retrieve data from 
+  the primary replica set member, or secondary members if the primary is unavailable
+- ``AVAILABLE`` read concern: Read operations return the instance's most recent data 
+  without guaranteeing that the data has been written to a majority of the replica
+  set members
+- ``MAJORITY`` write concern: The majority of all replica set members
+  must acknowledge the write operation
 
 .. literalinclude:: /includes/databases-collections/databases-collections.php
     :language: php
@@ -153,9 +190,16 @@ array to the ``selectDatabase()`` method:
 Collection Configuration Example
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The following example shows how to set the read preference, read concern, and
+This example shows how to set the read preference, read concern, and
 write concern of a collection called ``test_collection`` by passing an options
-array to the ``selectCollection()`` method:
+array to the ``selectCollection()`` method. The code configures the following settings:
+
+- ``SECONDARY_PREFERRED`` read preference: Read operations retrieve data from 
+  secondary replica set members, or the primary members if no secondaries are available
+- ``AVAILABLE`` read concern: Read operations return the instance's most recent data 
+  without guaranteeing that the data has been written to a majority of the replica
+  set members
+- ``0`` write concern: Requests no acknowledgment of the write operation
 
 .. literalinclude:: /includes/databases-collections/databases-collections.php
     :language: php