func()

in go/rows.go [134:226]

• 77 lines of code
• 29 McCabe index (conditional complexity)

func (r *Rows) fetchNextPage(token *string) error {
	var err error
	r.ResultOutput, err = r.athena.GetQueryResultsWithContext(r.ctx,
		&athena.GetQueryResultsInput{
			QueryExecutionId: aws.String(r.queryID),
			NextToken:        token,
		})
	if err != nil {
		r.tracer.Scope().Counter(DriverName + ".failure.fetchnextpage.getqueryresults").Inc(1)
		r.tracer.Log(ErrorLevel, "GetQueryResults failed", zap.String("error", err.Error()))
		r.reachedLastPage = true
		return err
	}

	r.pageCount++
	// First row of the first page contains header if the query is not DDL.
	// These are also available in *athenaAPI.Row.ResultSetMetadata.
	// Sometimes Athena go API will return row data without corresponding ColumnInfo. To circumvent this situation,
	// we choose to name the column as `column` + 0-index-based number
	// One example is:
	//   input:
	//      MSCK REPAIR TABLE sampledb.elb_logs
	//   output:
	//     _col0
	//     Partitions not in metastore:    elb_logs:2015/01/01     elb_logs:2015/01/02     elb_logs:2015/01/03
	//       elb_logs:2015/01/04     elb_logs:2015/01/05     elb_logs:2015/01/06     elb_logs:2015/01/07
	if r.ResultOutput != nil &&
		r.ResultOutput.ResultSet.ResultSetMetadata != nil &&
		r.ResultOutput.ResultSet.ResultSetMetadata.ColumnInfo != nil {
		rowLen := len(r.ResultOutput.ResultSet.Rows)
		colLen := len(r.ResultOutput.ResultSet.ResultSetMetadata.ColumnInfo)
		if rowLen > 0 {
			rowColLen := len(r.ResultOutput.ResultSet.Rows[0].Data)
			if colLen < rowColLen {
				for i := 0; i < rowColLen-colLen; i++ {
					colName := "_col" + strconv.Itoa(i+colLen)
					colType := "string"
					colInfo := newColumnInfo(colName, colType)
					r.ResultOutput.ResultSet.ResultSetMetadata.ColumnInfo = append(r.ResultOutput.ResultSet.ResultSetMetadata.ColumnInfo,
						colInfo)
				}
			} else if colLen > rowColLen && rowColLen == 1 {
				for k := 0; k < rowLen; k++ {
					items := strings.Split(*r.ResultOutput.ResultSet.Rows[k].Data[0].VarCharValue, "\t")
					if len(items) == colLen {
						for i, v := range items {
							items[i] = strings.TrimSpace(v)
						}
						r.ResultOutput.ResultSet.Rows[k] = newRow(colLen, items)
					}
				}
			}
		} else if rowLen == 0 && colLen == 1 && r.ResultOutput.UpdateCount != nil {
			if *r.ResultOutput.UpdateCount > 0 {
				if *r.ResultOutput.ResultSet.ResultSetMetadata.ColumnInfo[0].Name == "rows" {
					// For DML's INSERT INTO, DDL's CTAS
					updateCount := strconv.FormatInt(*r.ResultOutput.UpdateCount, 10)
					rData := athena.Datum{VarCharValue: &updateCount}
					aRow := athena.Row{Data: []*athena.Datum{&rData}}
					r.ResultOutput.ResultSet.Rows = append(r.ResultOutput.ResultSet.Rows, &aRow)
				}
			}
		}
	}
	var rowOffset = 0
	if r.pageCount == 0 {
		rs := r.ResultOutput.ResultSet
		ci := r.ResultOutput.ResultSet.ResultSetMetadata.ColumnInfo
		i := 0
		if len(ci) > 0 && len(rs.Rows) > 0 && len(rs.Rows[0].Data) > 0 && len(rs.Rows[0].Data) == len(ci) {
			for ; i < len(ci); i++ {
				if rs.Rows[0].Data[i] == nil || rs.Rows[0].Data[i].VarCharValue == nil {
					break
				}
				if *ci[i].Name != *rs.Rows[0].Data[i].VarCharValue {
					break
				}
			}
			if i == len(ci) {
				rowOffset = 1
			}
		}
	}

	// if there is no new row, we should not continue, and this also filters out cases that Rows is nil
	if len(r.ResultOutput.ResultSet.Rows) <= rowOffset {
		r.reachedLastPage = true
		return nil
	}

	r.ResultOutput.ResultSet.Rows = r.ResultOutput.ResultSet.Rows[rowOffset:]
	return nil
}