executor: set the correct stmtCtx for explain statement (#11186) (#11978

)

executor/executor.go

@@ -1346,13 +1346,18 @@ func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
 	default:
 		sc.MemTracker.SetActionOnExceed(&memory.LogOnExceed{})
 	}
-
 	if execStmt, ok := s.(*ast.ExecuteStmt); ok {
 		s, err = getPreparedStmt(execStmt, vars)
 		if err != nil {
 			return
 		}
 	}
+	// execute missed stmtID uses empty sql
+	sc.OriginalSQL = s.Text()
+	if explainStmt, ok := s.(*ast.ExplainStmt); ok {
+		sc.CastStrToIntStrict = true
+		s = explainStmt.Stmt
+	}
 	// TODO: Many same bool variables here.
 	// We should set only two variables (
 	// IgnoreErr and StrictSQLMode) to avoid setting the same bool variables and

executor/point_get_test.go

@@ -176,7 +176,7 @@ func (s *testPointGetSuite) TestIndexLookupCharPK(c *C) {
 	// Test truncate with sql mode `PAD_CHAR_TO_FULL_LENGTH`.
 	tk.MustExec(`set @@sql_mode="PAD_CHAR_TO_FULL_LENGTH";`)
 	tk.MustIndexLookup(`select * from t tmp where a = "aa";`).Check(testkit.Rows(`aa bb`))
-	tk.MustIndexLookup(`select * from t tmp where a = "aab";`).Check(testkit.Rows())
+	tk.MustTableDual(`select * from t tmp where a = "aab";`).Check(testkit.Rows())
 
 	tk.MustExec(`truncate table t;`)
 	tk.MustExec(`insert into t values("a ", "b ");`)
@@ -189,9 +189,9 @@ func (s *testPointGetSuite) TestIndexLookupCharPK(c *C) {
 
 	// Test trailing spaces with sql mode `PAD_CHAR_TO_FULL_LENGTH`.
 	tk.MustExec(`set @@sql_mode="PAD_CHAR_TO_FULL_LENGTH";`)
-	tk.MustIndexLookup(`select * from t tmp where a = "a";`).Check(testkit.Rows())
+	tk.MustTableDual(`select * from t tmp where a = "a";`).Check(testkit.Rows())
 	tk.MustIndexLookup(`select * from t tmp where a = "a ";`).Check(testkit.Rows(`a b`))
-	tk.MustIndexLookup(`select * from t tmp where a = "a  ";`).Check(testkit.Rows())
+	tk.MustTableDual(`select * from t tmp where a = "a  ";`).Check(testkit.Rows())
 
 	// Test CHAR BINARY.
 	tk.MustExec(`drop table if exists t;`)

util/testkit/testkit.go

@@ -185,6 +185,20 @@ func (tk *TestKit) MustIndexLookup(sql string, args ...interface{}) *Result {
 	return tk.MustQuery(sql, args...)
 }
 
+// MustTableDual checks whether the plan for the sql is TableDual.
+func (tk *TestKit) MustTableDual(sql string, args ...interface{}) *Result {
+	rs := tk.MustQuery("explain "+sql, args...)
+	hasTableDual := false
+	for i := range rs.rows {
+		if strings.Contains(rs.rows[i][0], "TableDual") {
+			hasTableDual = true
+			break
+		}
+	}
+	tk.c.Assert(hasTableDual, check.IsTrue)
+	return tk.MustQuery(sql, args...)
+}
+
 // MustPointGet checks whether the plan for the sql is Point_Get.
 func (tk *TestKit) MustPointGet(sql string, args ...interface{}) *Result {
 	rs := tk.MustQuery("explain "+sql, args...)