sysvar: update doc for tidb_opt_prefer_range_scan

pingcap · Sep 6, 2021 · 5b8fdb3 · 5b8fdb3
1 parent 7f8909a
commit 5b8fdb3
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/system-variables.md b/system-variables.md
@@ -1106,10 +1106,10 @@ mysql> desc select count(distinct a) from test.t;
 
 ### tidb_opt_prefer_range_scan <span class="version-mark">New in v5.0</span>
 
-- Scope: SESSION
+- Scope: SESSION | GLOBAL
 - Default value: `OFF`
-- After you set the value of this variable to `1`, the optimizer always prefers index scans over full table scans.
-- In the following example, before you enable `tidb_opt_prefer_range_scan`, the TiDB optimizer performs a full table scan. After you enable `tidb_opt_prefer_range_scan`, the optimizer selects an index scan.
+- After you set the value of this variable to `ON`, the optimizer always prefers range scans over full table scans.
+- In the following example, before you enable `tidb_opt_prefer_range_scan`, the TiDB optimizer performs a full table scan. After you enable `tidb_opt_prefer_range_scan`, the optimizer selects an index range scan.
 
 ```sql
 explain select * from t where age=5;