1 files changed, 125 insertions, 0 deletions
diff --git a/sql/abstractSchemaChanges/patch-templatelinks-tl_title-nullable.json b/sql/abstractSchemaChanges/patch-templatelinks-tl_title-nullable.json
new file mode 100644
index 000000000000..bfbbe7c2aca1
--- /dev/null
+++ b/sql/abstractSchemaChanges/patch-templatelinks-tl_title-nullable.json
@@ -0,0 +1,125 @@
+{
+	"comment": "Changing the primary key as part of normalizing templatelinks (T306674)",
+	"before": {
+		"name": "templatelinks",
+		"comment": "Track template inclusions. The target page may or may not exist, and due to renames and deletions may refer to different page records as time goes by.",
+		"columns": [
+			{
+				"name": "tl_from",
+				"comment": "Key to the page_id of the page containing the link.",
+				"type": "integer",
+				"options": { "notnull": true, "unsigned": true, "default": 0 }
+			},
+			{
+				"name": "tl_from_namespace",
+				"type": "integer",
+				"comment": "Namespace for this page",
+				"options": { "notnull": true, "default": 0 }
+			},
+			{
+				"name": "tl_namespace",
+				"type": "integer",
+				"options": { "notnull": true, "default": 0 }
+			},
+			{
+				"name": "tl_title",
+				"type": "binary",
+				"options": { "notnull": true, "length": 255, "default": "" }
+			},
+			{
+				"name": "tl_target_id",
+				"type": "bigint",
+				"comment": "Foreign key to linktarget.lt_id",
+				"options": { "notnull": false, "unsigned": true, "default": null }
+			}
+		],
+		"indexes": [
+			{
+				"name": "tl_namespace",
+				"columns": [ "tl_namespace", "tl_title", "tl_from" ],
+				"comment": "Reverse index, for Special:Whatlinkshere",
+				"unique": false
+			},
+			{
+				"name": "tl_backlinks_namespace",
+				"columns": [ "tl_from_namespace", "tl_namespace", "tl_title", "tl_from" ],
+				"comment": "Index for Special:Whatlinkshere with namespace filter",
+				"unique": false
+			},
+			{
+				"name": "tl_target_id",
+				"columns": [ "tl_target_id", "tl_from" ],
+				"comment": "Reverse index, for Special:Whatlinkshere",
+				"unique": false
+			},
+			{
+				"name": "tl_backlinks_namespace_target_id",
+				"columns": [ "tl_from_namespace", "tl_target_id", "tl_from" ],
+				"comment": "Index for Special:Whatlinkshere with namespace filter",
+				"unique": false
+			}
+		],
+		"pk": [ "tl_from", "tl_namespace", "tl_title" ]
+	},
+	"after": {
+		"name": "templatelinks",
+		"comment": "Track template inclusions. The target page may or may not exist, and due to renames and deletions may refer to different page records as time goes by.",
+		"columns": [
+			{
+				"name": "tl_from",
+				"comment": "Key to the page_id of the page containing the link.",
+				"type": "integer",
+				"options": { "notnull": true, "unsigned": true, "default": 0 }
+			},
+			{
+				"name": "tl_from_namespace",
+				"type": "integer",
+				"comment": "Namespace for this page",
+				"options": { "notnull": true, "default": 0 }
+			},
+			{
+				"name": "tl_namespace",
+				"type": "integer",
+				"options": { "default": 0 }
+			},
+			{
+				"name": "tl_title",
+				"type": "binary",
+				"options": { "length": 255, "default": "" }
+			},
+			{
+				"name": "tl_target_id",
+				"type": "bigint",
+				"comment": "Foreign key to linktarget.lt_id",
+				"options": { "notnull": true, "unsigned": true }
+			}
+		],
+		"indexes": [
+			{
+				"name": "tl_namespace",
+				"columns": [ "tl_namespace", "tl_title", "tl_from" ],
+				"comment": "Reverse index, for Special:Whatlinkshere",
+				"unique": false
+			},
+			{
+				"name": "tl_backlinks_namespace",
+				"columns": [ "tl_from_namespace", "tl_namespace", "tl_title", "tl_from" ],
+				"comment": "Index for Special:Whatlinkshere with namespace filter",
+				"unique": false
+			},
+			{
+				"name": "tl_target_id",
+				"columns": [ "tl_target_id", "tl_from" ],
+				"comment": "Reverse index, for Special:Whatlinkshere",
+				"unique": false
+			},
+			{
+				"name": "tl_backlinks_namespace_target_id",
+				"columns": [ "tl_from_namespace", "tl_target_id", "tl_from" ],
+				"comment": "Index for Special:Whatlinkshere with namespace filter",
+				"unique": false
+			}
+		],
+		"pk": [ "tl_from", "tl_target_id" ]
+	}
+}