ddl: never write untouched index values to temp index

ddl/indexmergetest/merge_test.go

@@ -897,3 +897,44 @@ func TestAddIndexDuplicateAndWriteConflict(t *testing.T) {
 	tk.MustExec("admin check table t;")
 	tk.MustQuery("select * from t;").Check(testkit.Rows("1 1", "2 1"))
 }
+
+func TestAddIndexUpdateUntouchedValues(t *testing.T) {
+	store, dom := testkit.CreateMockStoreAndDomain(t)
+
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t(id int primary key, b int, k int);")
+	tk.MustExec("insert into t values (1, 1, 1);")
+
+	tk1 := testkit.NewTestKit(t, store)
+	tk1.MustExec("use test")
+
+	d := dom.DDL()
+	originalCallback := d.GetHook()
+	defer d.SetHook(originalCallback)
+	callback := &callback.TestDDLCallback{}
+	var runDML bool
+	callback.OnJobRunAfterExported = func(job *model.Job) {
+		if t.Failed() || runDML {
+			return
+		}
+		switch job.SchemaState {
+		case model.StateWriteReorganization:
+			_, err := tk1.Exec("begin;")
+			assert.NoError(t, err)
+			_, err = tk1.Exec("update t set k=k+1 where id = 1;")
+			assert.NoError(t, err)
+			_, err = tk1.Exec("insert into t values (2, 1, 2);")
+			// Should not report "invalid temp index value".
+			assert.NoError(t, err)
+			_, err = tk1.Exec("commit;")
+			assert.NoError(t, err)
+			runDML = true
+		}
+	}
+	d.SetHook(callback)
+
+	tk.MustGetErrCode("alter table t add unique index idx(b);", errno.ErrDupEntry)
+	tk.MustExec("admin check table t;")
+	tk.MustQuery("select * from t;").Check(testkit.Rows("1 1 2", "2 1 2"))
+}

table/tables/index.go

@@ -239,7 +239,12 @@ func (c *index) Create(sctx sessionctx.Context, txn kv.Transaction, indexedValue
 
 		if !distinct || skipCheck || opt.Untouched {
 			val := idxVal
-			if keyIsTempIdxKey && !opt.Untouched { // Untouched key-values never occur in the storage.
+			if opt.Untouched && (keyIsTempIdxKey || len(tempKey) > 0) {
+				// Untouched key-values never occur in the storage and the temp index is not public.
+				// It is unnecessary to write the untouched temp index key-values.
+				continue
+			}
+			if keyIsTempIdxKey {
 				tempVal := tablecodec.TempIndexValueElem{Value: idxVal, KeyVer: keyVer, Distinct: distinct}
 				val = tempVal.Encode(nil)
 			}
@@ -248,10 +253,8 @@ func (c *index) Create(sctx sessionctx.Context, txn kv.Transaction, indexedValue
 				return nil, err
 			}
 			if len(tempKey) > 0 {
-				if !opt.Untouched { // Untouched key-values never occur in the storage.
-					tempVal := tablecodec.TempIndexValueElem{Value: idxVal, KeyVer: keyVer, Distinct: distinct}
-					val = tempVal.Encode(nil)
-				}
+				tempVal := tablecodec.TempIndexValueElem{Value: idxVal, KeyVer: keyVer, Distinct: distinct}
+				val = tempVal.Encode(nil)
 				err = txn.GetMemBuffer().Set(tempKey, val)
 				if err != nil {
 					return nil, err