code: func (e *CheckIndexExec) Next(ctx context.Context, req *chunk.RecordBatch) error {
  	if e.done {
  		return nil
  	}
  	defer func() { e.done = true }()
  
  	err := admin.CheckIndicesCount(e.ctx, e.dbName, e.tableName, []string{e.idxName})
  	if err != nil {
  		return err
  	}
  	chk := e.src.newFirstChunk()
  	for {
  		err := e.src.Next(ctx, chunk.NewRecordBatch(chk))
  		if err != nil {
  			return err
  		}
  		if chk.NumRows() == 0 {
  			break
  		}
  	}
  	return nil
  }
docs: // Next implements the Executor Next interface.