diff --git a/_config/model.yml b/_config/model.yml
index cfb60c02aa6..4046feddb65 100644
--- a/_config/model.yml
+++ b/_config/model.yml
@@ -8,6 +8,8 @@ SilverStripe\Core\Injector\Injector:
     class: SilverStripe\ORM\FieldType\DBCurrency
   DBClassName:
     class: SilverStripe\ORM\FieldType\DBClassName
+  DBClassNameVarchar:
+    class: SilverStripe\ORM\FieldType\DBClassNameVarchar
   Date:
     class: SilverStripe\ORM\FieldType\DBDate
   Datetime:
diff --git a/src/ORM/DatabaseAdmin.php b/src/ORM/DatabaseAdmin.php
index 8d08336fc22..5b222599b73 100644
--- a/src/ORM/DatabaseAdmin.php
+++ b/src/ORM/DatabaseAdmin.php
@@ -15,6 +15,7 @@
 use SilverStripe\ORM\Connect\DatabaseException;
 use SilverStripe\ORM\Connect\TableBuilder;
 use SilverStripe\ORM\FieldType\DBClassName;
+use SilverStripe\ORM\FieldType\DBClassNameVarchar;
 use SilverStripe\Security\Permission;
 use SilverStripe\Security\Security;
 use SilverStripe\Versioned\Versioned;
@@ -460,7 +461,8 @@ protected function getClassNameRemappingFields()
         foreach ($dataClasses as $className) {
             $fieldSpecs = $schema->fieldSpecs($className);
             foreach ($fieldSpecs as $fieldName => $fieldSpec) {
-                if (Injector::inst()->create($fieldSpec, 'Dummy') instanceof DBClassName) {
+                $dummy = Injector::inst()->create($fieldSpec, 'Dummy');
+                if ($dummy instanceof DBClassName || $dummy instanceof DBClassNameVarchar) {
                     $remapping[$className][] = $fieldName;
                 }
             }
diff --git a/src/ORM/FieldType/DBClassName.php b/src/ORM/FieldType/DBClassName.php
index 4848b05734e..0406f1c4111 100644
--- a/src/ORM/FieldType/DBClassName.php
+++ b/src/ORM/FieldType/DBClassName.php
@@ -2,47 +2,15 @@
 
 namespace SilverStripe\ORM\FieldType;
 
-use SilverStripe\Core\ClassInfo;
-use SilverStripe\Core\Config\Config;
-use SilverStripe\ORM\DataObject;
 use SilverStripe\ORM\DB;
+use SilverStripe\Core\Config\Config;
 
 /**
  * Represents a classname selector, which respects obsolete clasess.
  */
 class DBClassName extends DBEnum
 {
-
-    /**
-     * Base classname of class to enumerate.
-     * If 'DataObject' then all classes are included.
-     * If empty, then the baseClass of the parent object will be used
-     *
-     * @var string|null
-     */
-    protected $baseClass = null;
-
-    /**
-     * Parent object
-     *
-     * @var DataObject|null
-     */
-    protected $record = null;
-
-    private static $index = true;
-
-    /**
-     * Create a new DBClassName field
-     *
-     * @param string      $name      Name of field
-     * @param string|null $baseClass Optional base class to limit selections
-     * @param array       $options   Optional parameters for this DBField instance
-     */
-    public function __construct($name = null, $baseClass = null, $options = [])
-    {
-        $this->setBaseClass($baseClass);
-        parent::__construct($name, null, null, $options);
-    }
+    use DBClassNameTrait;
 
     /**
      * @return void
@@ -67,82 +35,6 @@ public function requireField()
         DB::require_field($this->getTable(), $this->getName(), $values);
     }
 
-    /**
-     * Get the base dataclass for the list of subclasses
-     *
-     * @return string
-     */
-    public function getBaseClass()
-    {
-        // Use explicit base class
-        if ($this->baseClass) {
-            return $this->baseClass;
-        }
-        // Default to the basename of the record
-        $schema = DataObject::getSchema();
-        if ($this->record) {
-            return $schema->baseDataClass($this->record);
-        }
-        // During dev/build only the table is assigned
-        $tableClass = $schema->tableClass($this->getTable());
-        if ($tableClass && ($baseClass = $schema->baseDataClass($tableClass))) {
-            return $baseClass;
-        }
-        // Fallback to global default
-        return DataObject::class;
-    }
-
-    /**
-     * Get the base name of the current class
-     * Useful as a non-fully qualified CSS Class name in templates.
-     *
-     * @return string|null
-     */
-    public function getShortName()
-    {
-        $value = $this->getValue();
-        if (empty($value) || !ClassInfo::exists($value)) {
-            return null;
-        }
-        return ClassInfo::shortName($value);
-    }
-
-    /**
-     * Assign the base class
-     *
-     * @param string $baseClass
-     * @return $this
-     */
-    public function setBaseClass($baseClass)
-    {
-        $this->baseClass = $baseClass;
-        return $this;
-    }
-
-    /**
-     * Get list of classnames that should be selectable
-     *
-     * @return array
-     */
-    public function getEnum()
-    {
-        $classNames = ClassInfo::subclassesFor($this->getBaseClass());
-        $dataobject = strtolower(DataObject::class);
-        unset($classNames[$dataobject]);
-        return array_values($classNames ?? []);
-    }
-
-    public function setValue($value, $record = null, $markChanged = true)
-    {
-        parent::setValue($value, $record, $markChanged);
-
-        if ($record instanceof DataObject) {
-            $this->record = $record;
-        }
-
-        return $this;
-    }
-
     public function getDefault()
     {
         // Check for assigned default
@@ -151,15 +43,6 @@ public function getDefault()
             return $default;
         }
 
-        // Allow classes to set default class
-        $baseClass = $this->getBaseClass();
-        $defaultClass = Config::inst()->get($baseClass, 'default_classname');
-        if ($defaultClass &&  class_exists($defaultClass ?? '')) {
-            return $defaultClass;
-        }
-
-        // Fallback to first option
-        $enum = $this->getEnum();
-        return reset($enum);
+        return $this->getDefaultClassName();
     }
 }
diff --git a/src/ORM/FieldType/DBClassNameTrait.php b/src/ORM/FieldType/DBClassNameTrait.php
new file mode 100644
index 00000000000..b2d6aac1dd6
--- /dev/null
+++ b/src/ORM/FieldType/DBClassNameTrait.php
@@ -0,0 +1,131 @@
+<?php
+
+namespace SilverStripe\ORM\FieldType;
+
+use SilverStripe\Core\ClassInfo;
+use SilverStripe\Core\Config\Config;
+use SilverStripe\ORM\DataObject;
+
+trait DBClassNameTrait
+{
+    /**
+     * Base classname of class to enumerate.
+     * If 'DataObject' then all classes are included.
+     * If empty, then the baseClass of the parent object will be used
+     *
+     * @var string|null
+     */
+    protected $baseClass = null;
+
+    /**
+     * Parent object
+     *
+     * @var DataObject|null
+     */
+    protected $record = null;
+
+    private static $index = true;
+
+    /**
+     * Create a new DBClassName field
+     *
+     * @param string      $name      Name of field
+     * @param string|null $baseClass Optional base class to limit selections
+     * @param array       $options   Optional parameters for this DBField instance
+     */
+    public function __construct($name = null, $baseClass = null, $options = [])
+    {
+        $this->setBaseClass($baseClass);
+        parent::__construct($name, null, null, $options);
+    }
+
+    /**
+     * Get the base dataclass for the list of subclasses
+     *
+     * @return string
+     */
+    public function getBaseClass()
+    {
+        // Use explicit base class
+        if ($this->baseClass) {
+            return $this->baseClass;
+        }
+        // Default to the basename of the record
+        $schema = DataObject::getSchema();
+        if ($this->record) {
+            return $schema->baseDataClass($this->record);
+        }
+        // During dev/build only the table is assigned
+        $tableClass = $schema->tableClass($this->getTable());
+        if ($tableClass && ($baseClass = $schema->baseDataClass($tableClass))) {
+            return $baseClass;
+        }
+        // Fallback to global default
+        return DataObject::class;
+    }
+
+    /**
+     * Get the base name of the current class
+     * Useful as a non-fully qualified CSS Class name in templates.
+     *
+     * @return string|null
+     */
+    public function getShortName()
+    {
+        $value = $this->getValue();
+        if (empty($value) || !ClassInfo::exists($value)) {
+            return null;
+        }
+        return ClassInfo::shortName($value);
+    }
+
+    /**
+     * Assign the base class
+     *
+     * @param string $baseClass
+     * @return $this
+     */
+    public function setBaseClass($baseClass)
+    {
+        $this->baseClass = $baseClass;
+        return $this;
+    }
+
+    /**
+     * Get list of classnames that should be selectable
+     *
+     * @return array
+     */
+    public function getEnum()
+    {
+        $classNames = ClassInfo::subclassesFor($this->getBaseClass());
+        $dataobject = strtolower(DataObject::class);
+        unset($classNames[$dataobject]);
+        return array_values($classNames ?? []);
+    }
+
+    public function setValue($value, $record = null, $markChanged = true)
+    {
+        parent::setValue($value, $record, $markChanged);
+
+        if ($record instanceof DataObject) {
+            $this->record = $record;
+        }
+
+        return $this;
+    }
+    
+    private function getDefaultClassName()
+    {
+        // Allow classes to set default class
+        $baseClass = $this->getBaseClass();
+        $defaultClass = Config::inst()->get($baseClass, 'default_classname');
+        if ($defaultClass &&  class_exists($defaultClass ?? '')) {
+            return $defaultClass;
+        }
+
+        // Fallback to first option
+        $subClassNames = $this->getEnum();
+        return reset($subClassNames);
+    }
+}
diff --git a/src/ORM/FieldType/DBClassNameVarchar.php b/src/ORM/FieldType/DBClassNameVarchar.php
new file mode 100644
index 00000000000..16755ead430
--- /dev/null
+++ b/src/ORM/FieldType/DBClassNameVarchar.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace SilverStripe\ORM\FieldType;
+
+use SilverStripe\ORM\FieldType\DBVarchar;
+
+/**
+ * An alternative to DBClassName that stores the class name as a varchar instead of an enum
+ * This will use more disk space, though will prevent issues with long dev/builds on
+ * very large database tables when a ALTER TABLE queries are required to update the enum.
+ *
+ * Use the following config to use this class in your project:
+ *
+ * <code>
+ * SilverStripe\ORM\DataObject:
+ *   fixed_fields:
+ *     ClassName: DBClassNameVarchar
+ * </code>
+ */
+class DBClassNameVarchar extends DBVarchar
+{
+    use DBClassNameTrait;
+}
diff --git a/tests/php/ORM/DBClassNameVarcharTest.php b/tests/php/ORM/DBClassNameVarcharTest.php
new file mode 100644
index 00000000000..80dfe8aff35
--- /dev/null
+++ b/tests/php/ORM/DBClassNameVarcharTest.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace SilverStripe\ORM\Tests;
+
+use SilverStripe\Core\Config\Config;
+use SilverStripe\ORM\DataObject;
+use SilverStripe\ORM\FieldType\DBClassNameVarchar;
+use SilverStripe\ORM\FieldType\DBVarchar;
+use SilverStripe\ORM\Tests\DataObjectSchemaTest\HasFields;
+
+/**
+ * These unit tests test will change DBClassName to a varchar column
+ * and then test that the tests in DataObjectSchemaTest still pass
+ *
+ * There's also a test that a ClassName of an arbitary DataObject is a Varchar
+ */
+class DBClassNameVarcharTest extends DataObjectSchemaTest
+{
+    public function setup(): void
+    {
+        parent::setup();
+        $fixedFields = Config::inst()->get(DataObject::class, 'fixed_fields');
+        $fixedFields['ClassName'] = 'DBClassNameVarchar';
+        Config::modify()->set(DataObject::class, 'fixed_fields', $fixedFields);
+    }
+
+    public function testVarcharType(): void
+    {
+        /** @var DataObject $obj */
+        $obj = HasFields::create();
+        $class = get_class($obj->dbObject('ClassName'));
+        $this->assertSame(DBClassNameVarchar::class, $class);
+        $this->assertTrue(is_a($class, DBVarchar::class, true));
+    }
+}
diff --git a/tests/php/ORM/DataObjectSchemaGenerationTest.php b/tests/php/ORM/DataObjectSchemaGenerationTest.php
index 391c782c2f1..e5c04ce185e 100644
--- a/tests/php/ORM/DataObjectSchemaGenerationTest.php
+++ b/tests/php/ORM/DataObjectSchemaGenerationTest.php
@@ -200,7 +200,9 @@ public function testClassNameSpecGeneration()
         DBEnum::flushCache();
         $do1 = new TestObject();
         $fields = $schema->databaseFields(TestObject::class, false);
-        $this->assertEquals("DBClassName", $fields['ClassName']);
+        // May be overridden from DBClassName to DBClassNameVarchar by config
+        $expectedClassName = DataObject::config()->get('fixed_fields')['ClassName'];
+        $this->assertEquals($expectedClassName, $fields['ClassName']);
         $this->assertEquals(
             [
                 TestObject::class,
diff --git a/tests/php/ORM/DataObjectSchemaTest.php b/tests/php/ORM/DataObjectSchemaTest.php
index daa14152f68..e4d122e1b4f 100644
--- a/tests/php/ORM/DataObjectSchemaTest.php
+++ b/tests/php/ORM/DataObjectSchemaTest.php
@@ -165,6 +165,11 @@ public function testTableForObjectField()
     public function testFieldSpec(array $args, array $expected): void
     {
         $schema = DataObject::getSchema();
+        // May be overridden from DBClassName to DBClassNameVarchar by config
+        $expectedClassName = DataObject::config()->get('fixed_fields')['ClassName'];
+        if (array_key_exists('ClassName', $expected) && $expectedClassName !== 'DBClassName') {
+            $expected['ClassName'] = str_replace('DBClassName', $expectedClassName, $expected['ClassName']);
+        }
         $this->assertEquals($expected, $schema->fieldSpecs(...$args));
     }