CartoDB-SQL-API/batch/query_runner.js

'use strict';

var PSQL = require('cartodb-psql');

function QueryRunner() {
}

module.exports = QueryRunner;

QueryRunner.prototype.run = function (job_id, sql, userDatabaseMetadata, callback) {
    var pg = new PSQL(userDatabaseMetadata, {}, { destroyOnError: true });

    pg.query('SET statement_timeout=0', function (err) {
        if(err) {
            return callback(err);
        }

        // mark query to allow to users cancel their queries
        sql = '/* ' + job_id + ' */ ' + sql;

        pg.eventedQuery(sql, function (err, query) {
            if (err) {
                return callback(err);
            }

            query.on('error', callback);

            query.on('end', function (result) {
                // only if result is present then query is done sucessfully otherwise an error has happened
                // and it was handled by error listener
                if (result) {
                    callback(null, result);
                }
            });
        });
    });

};