feat(spanner): update query option samples with optimizerStatisticsPackage (GoogleCloudPlatform#1438)

Author: skuruppu

spanner/src/create_client_with_query_options.php

@@ -41,7 +41,12 @@ function create_client_with_query_options($instanceId, $databaseId)
 {
     $spanner = new SpannerClient([
         'queryOptions' => [
-            'optimizerVersion' => "1"
+            'optimizerVersion' => '1',
+            // Pin the statistics package used for this client instance to an
+            // older version. The list of available statistics packages can be
+            // found by querying the "INFORMATION_SCHEMA.SPANNER_STATISTICS"
+            // table.
+            'optimizerStatisticsPackage' => 'auto_20191128_14_47_22UTC'
         ]
     ]);
     $instance = $spanner->instance($instanceId);

spanner/src/query_data_with_query_options.php

@@ -47,7 +47,10 @@ function query_data_with_query_options($instanceId, $databaseId)
         'SELECT VenueId, VenueName, LastUpdateTime FROM Venues',
         [
             'queryOptions' => [
-                'optimizerVersion' => "1"
+                'optimizerVersion' => '1',
+                // Pin the statistics package to the latest version just for
+                // this query.
+                'optimizerStatisticsPackage' => 'latest'
             ]
         ]
     );