diff --git a/backends/clickhouse/clickhouse.go b/backends/clickhouse/clickhouse.go
index 31c14b4..66599d7 100644
--- a/backends/clickhouse/clickhouse.go
+++ b/backends/clickhouse/clickhouse.go
@@ -183,7 +183,7 @@ func (click *SClickhouseBackend) GetCreateSQLs(ts sqlchemy.ITableSpec) []string
 			createSql += fmt.Sprintf("\nTTL `%s` + INTERVAL %d %s", ttlCol.Name(), ttlCount, ttlUnit)
 		}
 		// set default time zone of table to UTC
-		createSql += "\nSETTINGS index_granularity=8192, allow_nullable_key=1"
+		createSql += "\nSETTINGS index_granularity=8192"
 	}
 	return []string{
 		createSql,