Golang Index.SeekFirst方法代碼示例

func checkIndexAndRecord(txn kv.Transaction, t table.Table, idx table.Index) error {
	it, err := idx.SeekFirst(txn)
	if err != nil {
		return errors.Trace(err)
	}
	defer it.Close()

	cols := make([]*table.Column, len(idx.Meta().Columns))
	for i, col := range idx.Meta().Columns {
		cols[i] = t.Cols()[col.Offset]
	}

	for {
		vals1, h, err := it.Next()
		if terror.ErrorEqual(err, io.EOF) {
			break
		} else if err != nil {
			return errors.Trace(err)
		}

		vals2, err := rowWithCols(txn, t, h, cols)
		if terror.ErrorEqual(err, kv.ErrNotExist) {
			record := &RecordData{Handle: h, Values: vals1}
			err = errDateNotEqual.Gen("index:%v != record:%v", record, nil)
		}
		if err != nil {
			return errors.Trace(err)
		}
		if !reflect.DeepEqual(vals1, vals2) {
			record1 := &RecordData{Handle: h, Values: vals1}
			record2 := &RecordData{Handle: h, Values: vals2}
			return errDateNotEqual.Gen("index:%v != record:%v", record1, record2)
		}
	}

	return nil
}

func (s *testDBSuite) testAddIndex(c *C) {
	done := make(chan struct{}, 1)

	num := 100
	// first add some rows
	for i := 0; i < num; i++ {
		s.mustExec(c, "insert into t1 values (?, ?, ?)", i, i, i)
	}

	go func() {
		s.mustExec(c, "create index c3_index on t1 (c3)")
		done <- struct{}{}
	}()

	deletedKeys := make(map[int]struct{})

	ticker := time.NewTicker(s.lease / 2)
	defer ticker.Stop()
LOOP:
	for {
		select {
		case <-done:
			break LOOP
		case <-ticker.C:
			step := 10
			// delete some rows, and add some data
			for i := num; i < num+step; i++ {
				n := rand.Intn(num)
				deletedKeys[n] = struct{}{}
				s.mustExec(c, "delete from t1 where c1 = ?", n)
				s.mustExec(c, "insert into t1 values (?, ?, ?)", i, i, i)
			}
			num += step
		}
	}

	// get exists keys
	keys := make([]int, 0, num)
	for i := 0; i < num; i++ {
		if _, ok := deletedKeys[i]; ok {
			continue
		}
		keys = append(keys, i)
	}

	// test index key
	for _, key := range keys {
		rows := s.mustQuery(c, "select c1 from t1 where c3 = ?", key)
		matchRows(c, rows, [][]interface{}{{key}})
	}

	// test delete key not in index
	for key := range deletedKeys {
		rows := s.mustQuery(c, "select c1 from t1 where c3 = ?", key)
		matchRows(c, rows, nil)
	}

	// test index range
	for i := 0; i < 100; i++ {
		index := rand.Intn(len(keys) - 3)
		rows := s.mustQuery(c, "select c1 from t1 where c3 >= ? limit 3", keys[index])
		matchRows(c, rows, [][]interface{}{{keys[index]}, {keys[index+1]}, {keys[index+2]}})
	}

	// TODO: support explain in future.
	//rows := s.mustQuery(c, "explain select c1 from t1 where c3 >= 100")

	//ay := dumpRows(c, rows)
	//c.Assert(strings.Contains(fmt.Sprintf("%v", ay), "c3_index"), IsTrue)

	// get all row handles
	ctx := s.s.(context.Context)
	t := s.testGetTable(c, "t1")
	handles := make(map[int64]struct{})
	err := t.IterRecords(ctx, t.FirstKey(), t.Cols(), func(h int64, data []types.Datum, cols []*table.Column) (bool, error) {
		handles[h] = struct{}{}
		return true, nil
	})
	c.Assert(err, IsNil)

	// check in index
	var nidx table.Index
	for _, tidx := range t.Indices() {
		if tidx.Meta().Name.L == "c3_index" {
			nidx = tidx
			break
		}
	}
	// Make sure there is index with name c3_index
	c.Assert(nidx, NotNil)
	c.Assert(nidx.Meta().ID, Greater, int64(0))
	txn, err := ctx.GetTxn(true)
	c.Assert(err, IsNil)
	defer ctx.RollbackTxn()

	it, err := nidx.SeekFirst(txn)
	c.Assert(err, IsNil)
	defer it.Close()

	for {
//.........這裏部分代碼省略.........