Add index to civicrm_contact.created_date & modified_date

Note this will add the indexes to new installs or to installs who run the script to update indexes
(we used to promote this via a status check but there was a bug & we 'hushed' it & stopped trying to fix
the bug)

CRM/Contact/DAO/Contact.php

@@ -6,7 +6,7 @@
  *
  * Generated from xml/schema/CRM/Contact/Contact.xml
  * DO NOT EDIT.  Generated by CRM_Core_CodeGen
- * (GenCodeChecksum:bd37bd31a0ac8ba4fd5f411fddef080b)
+ * (GenCodeChecksum:f9efaf58b308bdcab56a0d5f9e76524f)
  */
 
 /**
@@ -1589,6 +1589,22 @@ public static function indices($localize = TRUE) {
         'localizable' => FALSE,
         'sig' => 'civicrm_contact::0::is_deleted::sort_name::id',
       ],
+      'index_created_date' => [
+        'name' => 'index_created_date',
+        'field' => [
+          0 => 'created_date',
+        ],
+        'localizable' => FALSE,
+        'sig' => 'civicrm_contact::0::created_date',
+      ],
+      'index_modified_date' => [
+        'name' => 'index_modified_date',
+        'field' => [
+          0 => 'modified_date',
+        ],
+        'localizable' => FALSE,
+        'sig' => 'civicrm_contact::0::modified_date',
+      ],
     ];
     return ($localize && !empty($indices)) ? CRM_Core_DAO_AllCoreTables::multilingualize(__CLASS__, $indices) : $indices;
   }

xml/schema/Contact/Contact.xml

@@ -874,6 +874,11 @@
     <default>NULL</default>
     <add>4.3</add>
   </field>
+  <index>
+    <name>index_created_date</name>
+    <fieldName>created_date</fieldName>
+    <add>5.18</add>
+  </index>
   <field>
     <name>modified_date</name>
     <type>timestamp</type>
@@ -883,4 +888,9 @@
     <default>CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP</default>
     <add>4.3</add>
   </field>
+  <index>
+    <name>index_modified_date</name>
+    <fieldName>modified_date</fieldName>
+    <add>5.18</add>
+  </index>
 </table>