From cc95a63f41500b4a673123bb5056601a5f455cdd Mon Sep 17 00:00:00 2001
From: Yuanjia Zhang <zhangyuanjia@pingcap.com>
Date: Wed, 29 Mar 2023 09:38:54 +0800
Subject: [PATCH] planner: skip plan-cache for prepared queries with `INT in
 (Decimals...)` (#40312) (#42650)

close pingcap/tidb#40224
---
 executor/prepared_test.go           | 32 +++++++++++++++++++++++++++++
 planner/core/expression_rewriter.go | 12 +++--------
 2 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/executor/prepared_test.go b/executor/prepared_test.go
index 3e1f8e8ef40fd..4bee947f471f3 100644
--- a/executor/prepared_test.go
+++ b/executor/prepared_test.go
@@ -181,6 +181,38 @@ func TestIssue38533(t *testing.T) {
 	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
 }
 
+func TestIssue40224(t *testing.T) {
+	store, clean := testkit.CreateMockStore(t)
+	defer clean()
+
+	orgEnable := plannercore.PreparedPlanCacheEnabled()
+	defer func() {
+		plannercore.SetPreparedPlanCache(orgEnable)
+	}()
+	plannercore.SetPreparedPlanCache(true)
+	tk := testkit.NewTestKit(t, store)
+
+	tk.MustExec("use test")
+	tk.MustExec("create table t (a int, key(a))")
+	tk.MustExec("prepare st from 'select a from t where a in (?, ?)'")
+	tk.MustExec("set @a=1.0, @b=2.0")
+	tk.MustExec("execute st using @a, @b")
+	tk.MustExec("execute st using @a, @b")
+	tkProcess := tk.Session().ShowProcess()
+	ps := []*util.ProcessInfo{tkProcess}
+	tk.Session().SetSessionManager(&mockSessionManager1{PS: ps})
+	rs := tk.MustQuery(fmt.Sprintf("explain for connection %d", tkProcess.ID))
+	require.True(t, strings.Contains(rs.Rows()[1][0].(string), "RangeScan")) // range-scan instead of full-scan
+
+	tk.MustExec("set @a=1, @b=2")
+	tk.MustExec("execute st using @a, @b")
+	tk.MustExec("execute st using @a, @b")
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1")) // cacheable for INT
+	tk.MustExec("execute st using @a, @b")
+	rs = tk.MustQuery(fmt.Sprintf("explain for connection %d", tkProcess.ID))
+	require.True(t, strings.Contains(rs.Rows()[1][0].(string), "RangeScan")) // range-scan instead of full-scan
+}
+
 func TestIssue29850(t *testing.T) {
 	store, dom, err := newStoreWithBootstrap()
 	require.NoError(t, err)
diff --git a/planner/core/expression_rewriter.go b/planner/core/expression_rewriter.go
index 1071d5fd6ebc4..abf8e4ae4c392 100644
--- a/planner/core/expression_rewriter.go
+++ b/planner/core/expression_rewriter.go
@@ -1473,16 +1473,10 @@ func (er *expressionRewriter) inToExpression(lLen int, not bool, tp *types.Field
 			if c, ok := args[i].(*expression.Constant); ok {
 				var isExceptional bool
 				if expression.MaybeOverOptimized4PlanCache(er.sctx, []expression.Expression{c}) {
-					if c.GetType().EvalType() == types.ETString {
-						// To keep the result be compatible with MySQL, refine `int non-constant <cmp> str constant`
-						// here and skip this refine operation in all other cases for safety.
-						er.sctx.GetSessionVars().StmtCtx.SkipPlanCache = true
-						expression.RemoveMutableConst(er.sctx, []expression.Expression{c})
-					} else {
-						continue
+					if c.GetType().EvalType() == types.ETInt {
+						continue // no need to refine it
 					}
-				} else if er.sctx.GetSessionVars().StmtCtx.SkipPlanCache {
-					// We should remove the mutable constant for correctness, because its value may be changed.
+					er.sctx.GetSessionVars().StmtCtx.SkipPlanCache = true
 					expression.RemoveMutableConst(er.sctx, []expression.Expression{c})
 				}
 				args[i], isExceptional = expression.RefineComparedConstant(er.sctx, *leftFt, c, opcode.EQ)