Index: resources/sql/autopatches/20140226.dxcustom.1.fielddata.php
===================================================================
--- /dev/null
+++ resources/sql/autopatches/20140226.dxcustom.1.fielddata.php
@@ -0,0 +1,22 @@
+<?php
+
+$conn_w = id(new DifferentialRevision())->establishConnection('w');
+$rows = new LiskRawMigrationIterator($conn_w, 'differential_auxiliaryfield');
+
+echo "Modernizing Differential auxiliary field storage...\n";
+
+$table_name = id(new DifferentialCustomFieldStorage())->getTableName();
+foreach ($rows as $row) {
+  $id = $row['id'];
+  echo "Migrating row {$id}...\n";
+  queryfx(
+    $conn_w,
+    'INSERT IGNORE INTO %T (objectPHID, fieldIndex, fieldValue)
+      VALUES (%s, %s, %s)',
+    $table_name,
+    $row['revisionPHID'],
+    PhabricatorHash::digestForIndex($row['name']),
+    $row['value']);
+}
+
+echo "Done.\n";
Index: src/__phutil_library_map__.php
===================================================================
--- src/__phutil_library_map__.php
+++ src/__phutil_library_map__.php
@@ -2891,7 +2891,6 @@
     'DifferentialAuditorsFieldSpecification' => 'DifferentialFieldSpecification',
     'DifferentialAuthorField' => 'DifferentialCustomField',
     'DifferentialAuthorFieldSpecification' => 'DifferentialFieldSpecification',
-    'DifferentialAuxiliaryField' => 'DifferentialDAO',
     'DifferentialBlameRevisionFieldSpecification' => 'DifferentialFieldSpecification',
     'DifferentialBranchFieldSpecification' => 'DifferentialFieldSpecification',
     'DifferentialCCWelcomeMail' => 'DifferentialReviewRequestMail',
Index: src/applications/differential/editor/DifferentialRevisionEditor.php
===================================================================
--- src/applications/differential/editor/DifferentialRevisionEditor.php
+++ src/applications/differential/editor/DifferentialRevisionEditor.php
@@ -707,14 +707,14 @@
 
     $revision = $this->revision;
 
-    $fields = id(new DifferentialAuxiliaryField())->loadAllWhere(
-      'revisionPHID = %s AND name IN (%Ls)',
-      $revision->getPHID(),
-      array_keys($aux_map));
-    $fields = mpull($fields, null, 'getName');
+    $fields = id(new DifferentialCustomFieldStorage())->loadAllWhere(
+      'objectPHID = %s',
+      $revision->getPHID());
+    $fields = mpull($fields, null, 'getFieldIndex');
 
     foreach ($aux_map as $key => $val) {
-      $obj = idx($fields, $key);
+      $index = PhabricatorHash::digestForIndex($key);
+      $obj = idx($fields, $index);
       if (!strlen($val)) {
         // If the new value is empty, just delete the old row if one exists and
         // don't add a new row if it doesn't.
@@ -723,9 +723,9 @@
         }
       } else {
         if (!$obj) {
-          $obj = new DifferentialAuxiliaryField();
-          $obj->setRevisionPHID($revision->getPHID());
-          $obj->setName($key);
+          $obj = new DifferentialCustomFieldStorage();
+          $obj->setObjectPHID($revision->getPHID());
+          $obj->setFieldIndex($index);
         }
 
         if ($obj->getValue() !== $val) {
Index: src/applications/differential/storage/DifferentialAuxiliaryField.php
===================================================================
--- src/applications/differential/storage/DifferentialAuxiliaryField.php
+++ src/applications/differential/storage/DifferentialAuxiliaryField.php
@@ -1,20 +1,6 @@
 <?php
 
-final class DifferentialAuxiliaryField extends DifferentialDAO {
-
-  protected $revisionPHID;
-  protected $name;
-  protected $value;
-
-  public function setName($name) {
-    if (strlen($name) > 32) {
-      throw new Exception(
-        "Tried to set name '{$name}' for a Differential auxiliary field; ".
-        "auxiliary field names must be no longer than 32 characters.");
-    }
-    $this->name = $name;
-    return $this;
-  }
+final class DifferentialAuxiliaryField {
 
   public static function loadFromStorage(
     DifferentialRevision $revision,
@@ -24,11 +10,20 @@
     $storage_keys = array_filter(mpull($aux_fields, 'getStorageKey'));
     $field_data = array();
     if ($storage_keys) {
-      $field_data = id(new DifferentialAuxiliaryField())->loadAllWhere(
-        'revisionPHID = %s AND name IN (%Ls)',
+      $index_map = array();
+      foreach ($storage_keys as $key) {
+        $index_map[PhabricatorHash::digestForIndex($key)] = $key;
+      }
+
+      $index_data = id(new DifferentialCustomFieldStorage())->loadAllWhere(
+        'objectPHID = %s AND fieldIndex IN (%Ls)',
         $revision->getPHID(),
-        $storage_keys);
-      $field_data = mpull($field_data, 'getValue', 'getName');
+        array_keys($index_map));
+      $index_data = mpull($index_data, 'getFieldValue', 'getFieldIndex');
+
+      foreach ($index_data as $index => $data) {
+        $field_data[$index_map[$index]] = $data;
+      }
     }
 
     foreach ($aux_fields as $aux_field) {
Index: src/applications/differential/storage/DifferentialRevision.php
===================================================================
--- src/applications/differential/storage/DifferentialRevision.php
+++ src/applications/differential/storage/DifferentialRevision.php
@@ -209,13 +209,6 @@
         $inline->delete();
       }
 
-      $fields = id(new DifferentialAuxiliaryField())->loadAllWhere(
-        'revisionPHID = %s',
-        $this->getPHID());
-      foreach ($fields as $field) {
-        $field->delete();
-      }
-
       // we have to do paths a little differentally as they do not have
       // an id or phid column for delete() to act on
       $dummy_path = new DifferentialAffectedPath();