CODEWITHSUNDEEP
javacassandra
Alan Jurgensen
Alan Jurgensen

Reputation: 853

How do you get column names from cassandra-jdbc ResultSet?

Using the CQL syntax with cassandra-jdbc driver.... this doesnt work, just get empty strings:

      PreparedStatement pstmt = conn.prepareStatement("select * from myCF");
      ResultSet rset = pstmt.executeQuery();
      ResultSetMetaData rsmd = rset.getMetaData();
      int cols = rsmd.getColumnCount();
      pset.next();
      print rsmd.getColumnName(0);
      print pset.getString(0);
      ...

Apparently I have to use unwrap or something like that per row... Post full example please for when you dont know column names.

Upvotes: 0

Views: 2747

Answers (1)

Alan Jurgensen
Alan Jurgensen

Reputation: 853

OK this is what worked:

    ResultSet res = pstmt.executeQuery();
    CassandraResultSet crs = res.unwrap(CassandraResultSet.class);
    crs.next() ;
    ResultSetMetaData rsmd = crs.getMetaData();
        cols = rsmd.getColumnCount();
        for(int i=1 ; i <= cols ; i++) {
          String colNm = rsmd.getColumnName(i);
          String colVal = null;
          String colType = rsmd.getColumnTypeName(i);
          if (colType.equals("JdbcLong")) {
              colVal = "" + crs.getLong(i);
          } else if (colType.equals("JdbcInteger")) {
              colVal = "" + crs.getInt(i);
          } else {
              colVal = crs.getString(i);

Note that to get proper display of keys, columnnames, and values, I had to define a Column Family like below:

NOTE: you wont be able to understand your column names and values unless
you set the Cassandra Type hints via cassandra-cli.  To have a schema like below
where all un-referenced column types are UTF8Type:
   CREATE COLUMN FAMILY  MyColFam  WITH key_validation_class=UTF8Type
     AND default_validation_class=UTF8Type AND comparator=UTF8Type
     AND column_metadata = [ 
          {column_name: an_integer_column, validation_class: IntegerType}
         {column_name: a_long_column,     validation_class: LongType}
     ];

Upvotes: 1

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