distsql

type PartialResult interface {
	// Next returns the next rowData of the sub result.
	// If no more row to return, rowData would be nil.
	Next(context.Context) (rowData []types.Datum, err error)
	// Close closes the partial result.
	Close() error
}

type SelectResult interface {
	// Next gets the next partial result.
	Next(context.Context) (PartialResult, error)
	// NextRaw gets the next raw result.
	NextRaw(context.Context) ([]byte, error)
	// NextChunk reads the data into chunk.
	NextChunk(context.Context, *chunk.Chunk) error
	// Close closes the iterator.
	Close() error
	// Fetch fetches partial results from client.
	// The caller should call SetFields() before call Fetch().
	Fetch(context.Context)
	// ScanKeys gets the total scan row count.
	ScanKeys() int64
}