Update system-variables.md

system-variables.md

@@ -4282,7 +4282,7 @@ mysql> desc select count(distinct a) from test.t;
 - Default value: `""`
 - This variable is used to control some internal behaviors of the optimizer.
 - The optimizer's behavior might vary depending on user scenarios or SQL statements. This variable provides a more fine-grained control over the optimizer and helps to prevent performance regression after upgrading caused by behavior changes in the optimizer.
-- For a more detailed introduction, see [Optimizer Fix Controls](https://docs.pingcap.com/tidb/v7.2/optimizer-fix-controls).
+- For a more detailed introduction, see [Optimizer Fix Controls](https://docs-archive.pingcap.com/tidb/v7.2/optimizer-fix-controls).
 
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