Exemplo n.º 1
0
func readResult(rs ast.RecordSet, count int) {
	for count > 0 {
		x, err := rs.Next()
		if err != nil {
			log.Fatal(err)
		}
		if x == nil {
			log.Fatal(count)
		}
		count--
	}
	rs.Close()
}
Exemplo n.º 2
0
Arquivo: tidb.go Projeto: astaxie/tidb
// GetRows gets all the rows from a RecordSet.
func GetRows(rs ast.RecordSet) ([][]types.Datum, error) {
	if rs == nil {
		return nil, nil
	}
	var rows [][]types.Datum
	defer rs.Close()
	// Negative limit means no limit.
	for {
		row, err := rs.Next()
		if err != nil {
			return nil, errors.Trace(err)
		}
		if row == nil {
			break
		}
		rows = append(rows, row.Data)
	}
	return rows, nil
}
Exemplo n.º 3
0
// collectSamples collects sample from the result set, using Reservoir Sampling algorithm.
// See https://en.wikipedia.org/wiki/Reservoir_sampling
func (e *SimpleExec) collectSamples(result ast.RecordSet) (count int64, samples []*ast.Row, err error) {
	for {
		var row *ast.Row
		row, err = result.Next()
		if err != nil {
			return count, samples, errors.Trace(err)
		}
		if row == nil {
			break
		}
		if len(samples) < maxSampleCount {
			samples = append(samples, row)
		} else {
			shouldAdd := rand.Int63n(count) < maxSampleCount
			if shouldAdd {
				idx := rand.Intn(maxSampleCount)
				samples[idx] = row
			}
		}
		count++
	}
	return count, samples, nil
}