diff --git a/information-schema/information-schema-tidb-index-usage.md b/information-schema/information-schema-tidb-index-usage.md
index 917bb12b9dfd5..8cc84fe5ba815 100644
--- a/information-schema/information-schema-tidb-index-usage.md
+++ b/information-schema/information-schema-tidb-index-usage.md
@@ -101,6 +101,7 @@ The output is as follows:
 
 - The data in the `TIDB_INDEX_USAGE` table might be delayed by up to 5 minutes.
 - After TiDB restarts, the data in the `TIDB_INDEX_USAGE` table is cleared.
+- TiDB records index usage for a table only when the table has valid statistics.
 
 ## Read more