Home/ Questions/Q 7932341
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-03T20:59:16+00:00

I am fetching records from MySQL database using Java (JDBC). I have tables –

  • 0

I am fetching records from MySQL database using Java (JDBC). I have tables –
Stop_Times with 1.5 Million records and
Stops with 1 lac records.

I am using following code

ResultSet rs = stm.executeQuery("select distinct(stop_id) from Stop_Times force index (idx_stop_times) where agency_id = '" + agency_id + "' and route_type = " + route_type + " order by stop_id");

while(rs.next())
{
  stop_id.add(rs.getString("stop_id"));               
}

JSONArray jsonResult = new JSONArray();

String sql = "select * from Stops force index (idx_Stops) where stop_id = ? and agency_id = ? and location_type = 0 order by stop_name";

                  PreparedStatement pstm = con.prepareStatement(sql);

                  int rid = 0;

                  for(int r = 0; r < stop_id.size(); r++)
                  {
                      pstm.setString(1, stop_id.get(r).toString());
                      pstm.setString(2, agency_id);
                      rs = pstm.executeQuery();

                      if(rs.next())
                      {
                          JSONObject jsonStop = new JSONObject();
                          jsonStop.put("str_station_id", rs.getString("stop_id"));
                          jsonStop.put("str_station_name", rs.getString("stop_name") + "_" + rs.getString("stop_id"));
                          jsonStop.put("str_station_code", rs.getString("stop_code"));
                          jsonStop.put("str_station_desc", rs.getString("stop_desc"));
                          jsonStop.put("str_station_lat", rs.getDouble("stop_lat"));
                          jsonStop.put("str_station_lon", rs.getDouble("stop_lon"));
                          jsonStop.put("str_station_url", rs.getString("stop_url"));
                          jsonStop.put("str_location_type", rs.getString("location_type"));
                          jsonStop.put("str_zone_id", rs.getString("zone_id"));

                          jsonResult.put((rid++), jsonStop);
                      }                               
                  }

The first query returns 6871 records. But it is taking too much time – on server side it is taking 8-10 seconds and at client side 40-45 seconds.

I want to reduce these times as for server side 300-500 milliseconds and at client side around 10 sec.
Please can anybody help me for how to to this?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Your strategy is to use a first query to get IDs, and then loop over these IDs and execute another query for each of the IDs found by the first query. You’re in fact doing a “manual” join instead of letting the database do it for you. You could rewrite everything in a single query:

    select * from Stops stops
inner join Stop_Times stopTimes on stopTimes.stop_id = stops.stop_id
where stops.stop_id = ? 
  and stops.agency_id = ? 
  and stops.location_type = 0 
  and stopTimes.agency_id = ? 
  and stopTimes.route_type = ?
order by stops.stop_name
    • 0