Beispiel #1
0
func intensityReported(start, end time.Time) (*haz.Shaking, error) {

	// query the DB twice.  MMI is counted both times, the first time
	// in the geohash, the second time as totals.
	// This is a race. When there are lots of reports being submitted
	// the total counts could be different between the two queries.
	// Seems like an acceptable trade off between a more complex query
	// (creating JSON and then unmarshallaing it) or doing a lot of
	// aggregation in code (which requires iterating many rows outside the db).

	rows, err := db.Query(`SELECT
  				ST_X(st_pointfromgeohash(geohash6)),
  				ST_Y(st_pointfromgeohash(geohash6)),
  				max(mmi),
  				count(mmi)
			       FROM impact.intensity_reported
				WHERE time >= $1 AND time <= $2
				GROUP BY geohash6`, start, end)

	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var s haz.Shaking

	for rows.Next() {
		var m haz.MMI
		if err = rows.Scan(&m.Longitude, &m.Latitude, &m.Mmi, &m.Count); err != nil {
			return nil, err
		}
		s.Mmi = append(s.Mmi, &m)
	}

	rows.Close()

	rows, err = db.Query(`SELECT mmi, count(mmi) FROM impact.intensity_reported
				WHERE time >= $1 AND time <= $2
				GROUP BY mmi`, start, end)

	if err != nil {
		return nil, err
	}
	defer rows.Close()

	s.MmiSummary = make(map[int32]int32)

	for rows.Next() {
		var k, v int32
		if err = rows.Scan(&k, &v); err != nil {
			return nil, err
		}
		s.MmiSummary[k] = v
		s.MmiTotal += v
	}

	return &s, nil
}
Beispiel #2
0
func intensityMeasuredLatest() (*haz.Shaking, error) {
	// there is only one mmi at each point for measured so no need to handle count anywhere
	rows, err := db.Query(`SELECT ST_X(location::geometry), ST_Y(location::geometry), mmi
					FROM impact.intensity_measured`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var s haz.Shaking
	s.MmiSummary = make(map[int32]int32)

	for rows.Next() {
		var m haz.MMI
		if err = rows.Scan(&m.Longitude, &m.Latitude, &m.Mmi); err != nil {
			return nil, err
		}
		s.Mmi = append(s.Mmi, &m)
		s.MmiTotal++
		s.MmiSummary[m.Mmi]++
	}

	return &s, nil
}