ddl: skip deleting the unmatched index key on merge (#40465) (#40478)

close #40464

ddl/index_merge_tmp.go

@@ -59,6 +59,15 @@ func (w *mergeIndexWorker) batchCheckTemporaryUniqueKey(txn kv.Transaction, idxR
  }
  if !idxRecords[i].delete {
  idxRecords[i].skip = true
+ } else {
+ // Prevent deleting an unexpected index KV.
+ hdInVal, err := tablecodec.DecodeHandleInUniqueIndexValue(val, w.table.Meta().IsCommonHandle)
+ if err != nil {
+ return errors.Trace(err)
+ }
+ if !idxRecords[i].handle.Equal(hdInVal) {
+ idxRecords[i].skip = true
+ }
  }
  } else if idxRecords[i].distinct {
  // The keys in w.batchCheckKeys also maybe duplicate,
@@ -76,6 +85,7 @@ type temporaryIndexRecord struct {
  delete bool
  unique bool
  distinct bool
+ handle kv.Handle
  rowKey kv.Key
 }
 
@@ -137,7 +147,8 @@ func (w *mergeIndexWorker) BackfillDataInTxn(taskRange reorgBackfillTask) (taskC
 
  // Lock the corresponding row keys so that it doesn't modify the index KVs
  // that are changing by a pessimistic transaction.
- err := txn.LockKeys(context.Background(), new(kv.LockCtx), idxRecord.rowKey)
+ rowKey := tablecodec.EncodeRecordKey(w.table.RecordPrefix(), idxRecord.handle)
+ err := txn.LockKeys(context.Background(), new(kv.LockCtx), rowKey)
  if err != nil {
  return errors.Trace(err)
  }
@@ -209,14 +220,13 @@ func (w *mergeIndexWorker) fetchTempIndexVals(txn kv.Transaction, taskRange reor
  return false, err
  }
  }
- rowKey := tablecodec.EncodeRecordKey(w.table.RecordPrefix(), handle)
 
  originIdxKey := make([]byte, len(indexKey))
  copy(originIdxKey, indexKey)
  tablecodec.TempIndexKey2IndexKey(w.index.Meta().ID, originIdxKey)
 
  idxRecord := &temporaryIndexRecord{
- rowKey: rowKey,
+ handle: handle,
  delete: isDelete,
  unique: unique,
  skip: false,

ddl/index_merge_tmp_test.go

@@ -378,6 +378,43 @@ func TestAddIndexMergeIndexUpdateOnDeleteOnly(t *testing.T) {
  tk.MustExec("admin check table t;")
 }
 
+func TestAddIndexMergeDeleteUniqueOnWriteOnly(t *testing.T) {
+ store, dom := testkit.CreateMockStoreAndDomain(t)
+
+ tk := testkit.NewTestKit(t, store)
+ tk.MustExec("use test")
+ tk.MustExec("create table t(a int default 0, b int default 0);")
+ tk.MustExec("insert into t values (1, 1), (2, 2), (3, 3), (4, 4);")
+
+ tk1 := testkit.NewTestKit(t, store)
+ tk1.MustExec("use test")
+
+ d := dom.DDL()
+ originalCallback := d.GetHook()
+ defer d.SetHook(originalCallback)
+ callback := &ddl.TestDDLCallback{}
+ onJobUpdatedExportedFunc := func(job *model.Job) {
+ if t.Failed() {
+ return
+ }
+ var err error
+ switch job.SchemaState {
+ case model.StateDeleteOnly:
+ _, err = tk1.Exec("insert into t values (5, 5);")
+ assert.NoError(t, err)
+ case model.StateWriteOnly:
+ _, err = tk1.Exec("insert into t values (5, 7);")
+ assert.NoError(t, err)
+ _, err = tk1.Exec("delete from t where b = 7;")
+ assert.NoError(t, err)
+ }
+ }
+ callback.OnJobUpdatedExported.Store(&onJobUpdatedExportedFunc)
+ d.SetHook(callback)
+ tk.MustExec("alter table t add unique index idx(a);")
+ tk.MustExec("admin check table t;")
+}
+
 func TestAddIndexMergeConflictWithPessimistic(t *testing.T) {
  store, dom := testkit.CreateMockStoreAndDomain(t)
  tk := testkit.NewTestKit(t, store)