From 389bc5fe608b6e35db1c8e4f05e40809917843ab Mon Sep 17 00:00:00 2001
From: Kenan Yao <cauchy1992@gmail.com>
Date: Thu, 18 Mar 2021 14:03:36 +0800
Subject: [PATCH] sessionctx: hide extended stats variable in SHOW VARIABLES
 temporarily (#23345)

---
 sessionctx/variable/tidb_vars.go |  1 +
 statistics/handle/handle_test.go | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/sessionctx/variable/tidb_vars.go b/sessionctx/variable/tidb_vars.go
index 5400eac9f944d..8acc5841bd1a6 100644
--- a/sessionctx/variable/tidb_vars.go
+++ b/sessionctx/variable/tidb_vars.go
@@ -713,6 +713,7 @@ var FeatureSwitchVariables = []string{
 	TiDBAnalyzeVersion,
 	TiDBPartitionPruneMode,
 	TiDBIntPrimaryKeyDefaultAsClustered,
+	TiDBEnableExtendedStats,
 }
 
 // FilterImplicitFeatureSwitch is used to filter result of show variables, these switches should be turn blind to users.
diff --git a/statistics/handle/handle_test.go b/statistics/handle/handle_test.go
index 20d837c3a956c..b4a2baca5da94 100644
--- a/statistics/handle/handle_test.go
+++ b/statistics/handle/handle_test.go
@@ -2091,3 +2091,14 @@ func (s *testStatsSuite) TestExtendedStatsPartitionTable(c *C) {
 	err = tk.ExecToErr("alter table t2 add stats_extended s1 correlation(b,c)")
 	c.Assert(err.Error(), Equals, "Extended statistics on partitioned tables are not supported now")
 }
+
+func (s *testStatsSuite) TestHideExtendedStatsSwitch(c *C) {
+	// NOTICE: remove this test when this extended-stats reaches GA state.
+	defer cleanEnv(c, s.store, s.do)
+	tk := testkit.NewTestKit(c, s.store)
+	rs := tk.MustQuery("show variables").Rows()
+	for _, r := range rs {
+		c.Assert(strings.ToLower(r[0].(string)), Not(Equals), "tidb_enable_extended_stats")
+	}
+	tk.MustQuery("show variables like 'tidb_enable_extended_stats'").Check(testkit.Rows())
+}