code: func (e *TableScanExec) Next(ctx context.Context, req *chunk.RecordBatch) error {
  	if span := opentracing.SpanFromContext(ctx); span != nil && span.Tracer() != nil {
  		span1 := span.Tracer().StartSpan("tableScan.Next", opentracing.ChildOf(span.Context()))
  		defer span1.Finish()
  	}
  	if e.runtimeStats != nil {
  		start := time.Now()
  		defer func() { e.runtimeStats.Record(time.Since(start), req.NumRows()) }()
  	}
  	req.GrowAndReset(e.maxChunkSize)
  	if e.isVirtualTable {
  		return e.nextChunk4InfoSchema(ctx, req.Chunk)
  	}
  	handle, found, err := e.nextHandle()
  	if err != nil || !found {
  		return err
  	}
  
  	mutableRow := chunk.MutRowFromTypes(e.retTypes())
  	for req.NumRows() < req.Capacity() {
  		row, err := e.getRow(handle)
  		if err != nil {
  			return err
  		}
  		e.seekHandle = handle + 1
  		mutableRow.SetDatums(row...)
  		req.AppendRow(mutableRow.ToRow())
  	}
  	return nil
  }
docs: // Next implements the Executor Next interface.