From 1bbc0a503318901809c19a620c721004a49bd098 Mon Sep 17 00:00:00 2001
From: tpp <terry.purcell@pingcap.com>
Date: Mon, 20 Oct 2025 16:39:13 -0700
Subject: [PATCH] planner: Add subquery variables

---
 system-variables.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/system-variables.md b/system-variables.md
index 27d4fec816dbc..86a806534d7f1 100644
--- a/system-variables.md
+++ b/system-variables.md
@@ -4104,6 +4104,24 @@ mysql> desc select count(distinct a) from test.t;
 - Default value: `OFF`
 - This variable controls whether to enable the [Cross-database binding](/sql-plan-management.md#cross-database-binding) feature.
 
+### tidb_opt_enable_no_decorrelate_in_select <span class="version-mark">New in v8.5.4</span>
+
+- Scope: SESSION | GLOBAL
+- Persists to cluster: Yes
+- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): Yes
+- Type: Boolean
+- Default value: `OFF`
+- This variable controls whether to apply the hint [`NO_DECORRELATE`](/optimizer-hints.md#no_decorrelate) at the session/global level for all queries with a subquery in the select list.
+
+### tidb_opt_enable_semi_join_rewrite <span class="version-mark">New in v8.5.4</span>
+
+- Scope: SESSION | GLOBAL
+- Persists to cluster: Yes
+- Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No
+- Type: Boolean
+- Default value: `OFF`
+- This variable controls whether to apply the hint [`SEMI_JOIN_REWRITE`](/optimizer-hints.md#semi_join_rewrite) at the session/global level for all queries that contain subqueries.
+
 ### tidb_opt_fix_control <span class="version-mark">New in v6.5.3 and v7.1.0</span>
 
 <CustomContent platform="tidb">