skip log slow query for DDL statement.

executor/adapter.go

@@ -507,12 +507,17 @@ func (a *ExecStmt) Exec(ctx context.Context) (_ sqlexec.RecordSet, err error) {
 				sql = ss.SecureText()
 			}
 		}
+
 		maxExecutionTime := getMaxExecutionTime(sctx)
 		// Update processinfo, ShowProcess() will use it.
-		pi.SetProcessInfo(sql, time.Now(), cmd, maxExecutionTime)
 		if a.Ctx.GetSessionVars().StmtCtx.StmtType == "" {
 			a.Ctx.GetSessionVars().StmtCtx.StmtType = ast.GetStmtLabel(a.StmtNode)
 		}
+		// Since maxExecutionTime is used only for query statement, here we limit it affect scope.
+		if !isQueryStmt(a.Ctx.GetSessionVars().StmtCtx.StmtType) {
+			maxExecutionTime = 0
+		}
+		pi.SetProcessInfo(sql, time.Now(), cmd, maxExecutionTime)
 	}
 
 	failpoint.Inject("mockDelayInnerSessionExecute", func() {
@@ -556,6 +561,14 @@ func (a *ExecStmt) Exec(ctx context.Context) (_ sqlexec.RecordSet, err error) {
 	}, nil
 }
 
+// check statement type with nodeType string from stmtNode.
+func isQueryStmt(nodeType string) bool {
+	if nodeType == "Select" || nodeType == "Execute" {
+		return true
+	}
+	return false
+}
+
 func (a *ExecStmt) handleStmtForeignKeyTrigger(ctx context.Context, e Executor) error {
 	stmtCtx := a.Ctx.GetSessionVars().StmtCtx
 	if stmtCtx.ForeignKeyTriggerCtx.HasFKCascades {

server/conn_test.go

@@ -729,6 +729,11 @@ func TestConnExecutionTimeout(t *testing.T) {
 
 	err = cc.handleQuery(context.Background(), "select /*+ MAX_EXECUTION_TIME(100)*/  * FROM testTable2 WHERE  SLEEP(1);")
 	require.NoError(t, err)
+
+	tk.MustExec("set @@max_execution_time = 500;")
+
+	err = cc.handleQuery(context.Background(), "alter table testTable2 add index idx(age);")
+	require.NoError(t, err)
 }
 
 func TestShutDown(t *testing.T) {