Quering and writing to a file : errorcode 28

Question

hi,

I am getting this error when I try to query the database and write results to a file. It never occured before.

java.sql.SQLException: Error writing file '/tmp/MYwADPLw' (Errcode: 28)

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:946) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2870) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1665) at com.mysql.jdbc.Connection.execSQL(Connection.java:3170) at com.mysql.jdbc.Connection.execSQL(Connection.java:3099) at com.mysql.jdbc.Statement.executeQuery(Statement.java:1169) at DBase.connect(DBase.java:58)
// this is where i call executequery at automateExport.main(automateExport.java:11) Exception in thread "main" java.lang.NullPointerException at automateExport.main(automateExport.java:13) // main class with db connection

The resultset I am expecting is very large. I never had this problem when I was querying for a smaller resultset. Could it be space issues? I have 117 gb on my disc. But I am expecting a max of 1gb text data. Any solutions???

My Code:

 public Connection connect(String db_connect_str,String db_userid, String db_password) {
        Connection conn;
        Statement stmt;
        String query;
     // inputfile - csv
        String input = "inputfile.txt";
        try {
         // to bifurcate heap memory error   
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            conn = DriverManager.getConnection(db_connect_str,db_userid, db_password);
            stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,  
                    java.sql.ResultSet.CONCUR_READ_ONLY);
            stmt.setFetchSize(Integer.MIN_VALUE); 

            query = "SELECT  r.name, r.network , r.namestring, i.name, i.description "+
            " , r.rid  , i.id, d.dtime ,d.ifInOctets , d.ifOutOctets , FROM_UNIXTIME(d.dtime)"+
            " FROM router AS r INNER JOIN interface AS i ON r.rid = i.rid " +
            "INNER JOIN  1278993600_1_60 AS d ON i.id = d.id " +
            "AND dtime BETWEEN " +startTime+ " AND "+ endTime +" WHERE r.network = 'ITPN'" +
                    "AND i.status = 'active' ORDER BY i.id, d.dtime";

            BufferedWriter fw = new BufferedWriter(new FileWriter(input));            
            ResultSet rs = stmt.executeQuery(query); 
            String idescp = null;
            // writing to file
            while (rs.next()) {
              if(rs.getString("description").equals(null)){
                  System.out.println("description" +rs.getString("description") );
                  idescp = "NA";
                  System.out.println("idescp :" +idescp + ":");
              }else{
                  idescp = rs.getString("description");
              }
              fw.write(rs.getString(1)+","+ rs.getString("rid")+","+ rs.getString("id") + "," +idescp+","
                      +rs.getString("dtime")+ "," +rs.getString("ifInOctets")+ "," + 
                      rs.getString("ifOutOctets") + ","+ rs.getString(11)+NL); 
            }

            fw.close();
            rs.close() ;
            stmt.close() ;
        } catch(Exception e) {
            e.printStackTrace();
            conn = null;
        }
        return conn;
    }

Please help. Thank you.

Answer 1

Maybe the database runs out of temp space on the file. I would check if ot the path given, the account the database is running on has the right and the space to write some data.

Answer 2

MySQL will write large resultsets to disk for streaming. The database server's /tmp folder is likely filling up as @Frank suggests.