planner: check the ignore-plan-cache hint in insert-stmt

executor/seqtest/prepared_test.go

@@ -420,14 +420,14 @@ func TestPreparedInsert(t *testing.T) {
 			err = counter.Write(pb)
 			require.NoError(t, err)
 			hit := pb.GetCounter().GetValue()
-			require.Equal(t, float64(1), hit)
+			require.Equal(t, float64(0), hit) // insert-values-stmt cannot use the plan cache
 		}
 		tk.MustExec(`set @a=3,@b=3; execute stmt_insert using @a, @b;`)
 		if flag {
 			err = counter.Write(pb)
 			require.NoError(t, err)
 			hit := pb.GetCounter().GetValue()
-			require.Equal(t, float64(2), hit)
+			require.Equal(t, float64(0), hit)
 		}
 
 		result := tk.MustQuery("select id, c1 from prepare_test where id = ?", 1)
@@ -443,21 +443,21 @@ func TestPreparedInsert(t *testing.T) {
 			err = counter.Write(pb)
 			require.NoError(t, err)
 			hit := pb.GetCounter().GetValue()
-			require.Equal(t, float64(2), hit)
+			require.Equal(t, float64(0), hit)
 		}
 		tk.MustExec(`set @a=2; execute stmt_insert_select using @a;`)
 		if flag {
 			err = counter.Write(pb)
 			require.NoError(t, err)
 			hit := pb.GetCounter().GetValue()
-			require.Equal(t, float64(3), hit)
+			require.Equal(t, float64(1), hit)
 		}
 		tk.MustExec(`set @a=3; execute stmt_insert_select using @a;`)
 		if flag {
 			err = counter.Write(pb)
 			require.NoError(t, err)
 			hit := pb.GetCounter().GetValue()
-			require.Equal(t, float64(4), hit)
+			require.Equal(t, float64(2), hit)
 		}
 
 		result = tk.MustQuery("select id, c1 from prepare_test where id = ?", 101)

planner/core/plan_cache_test.go

@@ -221,6 +221,29 @@ func TestIssue38533(t *testing.T) {
 	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
 }
 
+func TestIgnoreInsertStmt(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t (a int)")
+
+	// do not cache native insert-stmt
+	tk.MustExec("prepare st from 'insert into t values (1)'")
+	tk.MustExec("execute st")
+	tk.MustExec("execute st")
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
+
+	// ignore-hint in insert-stmt can work
+	tk.MustExec("prepare st from 'insert into t select * from t'")
+	tk.MustExec("execute st")
+	tk.MustExec("execute st")
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("1"))
+	tk.MustExec("prepare st from 'insert /*+ ignore_plan_cache() */ into t select * from t'")
+	tk.MustExec("execute st")
+	tk.MustExec("execute st")
+	tk.MustQuery("select @@last_plan_from_cache").Check(testkit.Rows("0"))
+}
+
 func TestIssue38710(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)

planner/core/plan_cacheable_checker.go

@@ -94,6 +94,21 @@ func (checker *cacheableChecker) Enter(in ast.Node) (out ast.Node, skipChildren
 				return in, true
 			}
 		}
+	case *ast.InsertStmt:
+		if node.Select == nil {
+			// do not cache insert-values-stmt like 'insert into t values (...)' since
+			// no performance benefit and to save memory.
+			checker.cacheable = false
+			checker.reason = "ignore insert-values-stmt"
+			return in, true
+		}
+		for _, hints := range node.TableHints {
+			if hints.HintName.L == HintIgnorePlanCache {
+				checker.cacheable = false
+				checker.reason = "ignore plan cache by hint"
+				return in, true
+			}
+		}
 	case *ast.VariableExpr, *ast.ExistsSubqueryExpr, *ast.SubqueryExpr:
 		checker.cacheable = false
 		checker.reason = "query has sub-queries is un-cacheable"

planner/core/plan_cacheable_checker_test.go

@@ -53,7 +53,9 @@ func TestCacheable(t *testing.T) {
 
 	tableRefsClause := &ast.TableRefsClause{TableRefs: &ast.Join{Left: &ast.TableSource{Source: tbl}}}
 	// test InsertStmt
-	stmt = &ast.InsertStmt{Table: tableRefsClause}
+	stmt = &ast.InsertStmt{Table: tableRefsClause} // insert-values-stmt
+	require.False(t, core.Cacheable(stmt, is))
+	stmt = &ast.InsertStmt{Table: tableRefsClause, Select: &ast.SelectStmt{}} // insert-select-stmt
 	require.True(t, core.Cacheable(stmt, is))
 
 	// test DeleteStmt