diff --git a/optimizer-fix-controls.md b/optimizer-fix-controls.md
index 4460cee3c820c..2d642c07e0b73 100644
--- a/optimizer-fix-controls.md
+++ b/optimizer-fix-controls.md
@@ -76,3 +76,13 @@ SET SESSION tidb_opt_fix_control = '44262:ON,44389:ON';
 - Default value: `OFF`
 - Possible values: `ON`, `OFF`
 - This variable controls whether the optimizer explores enforced plans during query optimization after finding an unenforced plan.
+
+### [`56318`](https://github.com/pingcap/tidb/issues/56318)
+
+> **Note:**
+>
+> This is only available for [TiDB Cloud Serverless](https://docs.pingcap.com/tidbcloud/select-cluster-tier#tidb-cloud-serverless).
+
+- Default value: `ON`
+- Possible values: `ON`, `OFF`
+- This variable controls whether to avoid calculating the heavy expression used in the `ORDER BY` statement twice.
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