code: func (e *RecoverIndexExec) Open(ctx context.Context) error {
  	if err := e.baseExecutor.Open(ctx); err != nil {
  		return err
  	}
  
  	e.srcChunk = chunk.New(e.columnsTypes(), e.initCap, e.maxChunkSize)
  	e.batchSize = 2048
  	e.recoverRows = make([]recoverRows, 0, e.batchSize)
  	e.idxValsBufs = make([][]types.Datum, e.batchSize)
  	e.idxKeyBufs = make([][]byte, e.batchSize)
  	return nil
  }
docs: // Open implements the Executor Open interface.