diff --git a/elastic search/elastic search.md b/elastic search/elastic search.md
index f4615bf..1df71f0 100644
--- a/elastic search/elastic search.md	
+++ b/elastic search/elastic search.md	
@@ -606,9 +606,10 @@ PUT /cooking_blog/_mapping
 > }
 > ```
 
-#### 将blog示例添加到索引中
-
-
+> #### ignore_above
+> 在`keyword`中指定`ignore_above`为256，将避免索引长度大于256的字段值。当字段长度大于256时，该字段将不会被索引，`但是被忽略字段将会包含在_source中`
+> 
+> 当`ignore_above`没有显式指定时，其值默认为256.