From ebd3fb6526eb3ee9359111e548d9f6b6e0323e97 Mon Sep 17 00:00:00 2001
From: Loz Calver <lozcalver@bigfork.co.uk>
Date: Tue, 20 Mar 2018 16:49:36 +0000
Subject: [PATCH] FIX: Don't auto-generate indexes for Text field types (fixes
 #7900)

---
 model/DataObject.php                           | 14 +++++++++++---
 model/fieldtypes/DBField.php                   |  8 ++++++++
 model/fieldtypes/Text.php                      |  2 ++
 tests/model/DataObjectSchemaGenerationTest.php | 17 ++++++++++++++++-
 4 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/model/DataObject.php b/model/DataObject.php
index f2946e98f..965d4c5ad 100644
--- a/model/DataObject.php
+++ b/model/DataObject.php
@@ -1789,7 +1789,7 @@ class DataObject extends ViewableData implements DataObjectInterface, i18nEntity
 		$result = $result->alterDataQuery(function($query) use ($extraFields) {
 			$query->setQueryParam('Component.ExtraFields', $extraFields);
 		});
-		
+
 		if($this->model) $result->setDataModel($this->model);
 
 		$this->extend('updateManyManyComponents', $result);
@@ -3421,7 +3421,15 @@ class DataObject extends ViewableData implements DataObjectInterface, i18nEntity
 						continue;
 					}
 
-					if ($this->hasOwnTableDatabaseField($column) && !array_key_exists($column, $indexes)) {
+					list($fieldType) = SS_Object::parse_class_spec($this->db($column));
+					$isAutoIndexable = (Config::inst()->get($fieldType, 'auto_indexable')
+						|| Config::inst()->get("DB{$fieldType}", 'auto_indexable'));
+
+					if (
+						$this->hasOwnTableDatabaseField($column)
+						&& !array_key_exists($column, $indexes)
+						&& $isAutoIndexable
+					) {
 						$indexes[$column] = true;
 					}
 				} catch (InvalidArgumentException $e) { }
@@ -3754,7 +3762,7 @@ class DataObject extends ViewableData implements DataObjectInterface, i18nEntity
 	 */
 	public function summaryFields() {
 		$rawFields = $this->stat('summary_fields');
-	
+
 		$fields = array();
 		// Merge associative / numeric keys
 		if (is_array($rawFields)) {
diff --git a/model/fieldtypes/DBField.php b/model/fieldtypes/DBField.php
index 8e0616857..acc2ea7ec 100644
--- a/model/fieldtypes/DBField.php
+++ b/model/fieldtypes/DBField.php
@@ -60,6 +60,14 @@ abstract class DBField extends ViewableData {
 	 */
 	private static $default_search_filter_class = 'PartialMatchFilter';
 
+	/**
+	 * Flag to indicate whether this data type is safe to automatically generate an index for
+	 *
+	 * @var bool
+	 * @config
+	 */
+	private static $auto_indexable = true;
+
 	/**
 	 * @var $default mixed Default-value in the database.
 	 * Might be overridden on DataObject-level, but still useful for setting defaults on
diff --git a/model/fieldtypes/Text.php b/model/fieldtypes/Text.php
index 7dbc2ed61..c0313d7f7 100644
--- a/model/fieldtypes/Text.php
+++ b/model/fieldtypes/Text.php
@@ -32,6 +32,8 @@ class Text extends StringField {
 		'LimitWordCountXML' => 'HTMLText',
 	);
 
+	private static $auto_indexable = false;
+
 	/**
  	 * (non-PHPdoc)
  	 * @see DBField::requireField()
diff --git a/tests/model/DataObjectSchemaGenerationTest.php b/tests/model/DataObjectSchemaGenerationTest.php
index 2641c2268..4ba8e719a 100644
--- a/tests/model/DataObjectSchemaGenerationTest.php
+++ b/tests/model/DataObjectSchemaGenerationTest.php
@@ -216,6 +216,11 @@ class DataObjectSchemaGenerationTest extends SapphireTest {
         $indexes = $object->databaseIndexes();
         $this->assertArrayHasKey('Sort', $indexes);
         $this->assertEquals('unique', $indexes['Sort']);
+
+        // make sure Text fields don't get indexes automatically - these can be db-driver dependent
+		$object = new DataObjectSchemaGenerationTest_SortedByText();
+		$indexes = $object->databaseIndexes();
+		$this->assertArrayNotHasKey('Description', $indexes);
 	}
 }
 
@@ -265,4 +270,14 @@ class DataObjectSchemaGenerationTest_Sorted extends DataObject implements TestOn
     );
 
     private static $default_sort = "Sort";
-}
\ No newline at end of file
+}
+
+class DataObjectSchemaGenerationTest_SortedByText extends DataObject implements TestOnly {
+	private static $db = array(
+		'Title' => 'Varchar',
+		'Description' => 'Text',
+		'Sort' => 'Int',
+	);
+
+	private static $default_sort = "Description";
+}