example profiling from minq < 1.0.0

gistfile1.js

 // rudimentary db query profiling
  var profile
  if (!config.profiledb) {
    profile = function (x) { return x }
  } else {

    var totalQueries = 0
    var profileLog = require('fs').createWriteStream('./dbprofile.log')
    var path = require('path')
    var base = path.resolve(path.join(__dirname, '..'))

    function blackbox(stacktrace) {
      try {
        return stacktrace.split('\n')
          .slice(2)
          .filter(function (frame) {
            return frame.indexOf('node_modules') < 0
              && !frame.match(/ \(\w+\.js:.+\)$/)
          })
          .map(function (frame) {
            return frame.replace(base, '')
          })
          .join('\n')
      } catch (e) {
        return stacktrace.split('\n')[2]
      }
    }

    profile = function (query) {
      var start = Date.now()
      var stack
      function report(results) {
          totalQueries++
          var end = Date.now()

          profileLog.write(JSON.stringify({
            n: totalQueries,
            time: end-start,
            projectionUsed: Object.keys(query._.projection || {}).length > 0,
            resultLength: results.length,
            resultSize: results.map(function (x) { return JSON.stringify(x) }).join('').length,
            collection: query._.collection,
            query: query._.query,
            at: blackbox(stack)
          }) + '\n')
      }

      query.one = function () {
        var promise = query.__proto__.one.call(query)
        stack = new Error().stack
        promise.then(function (result) {
          report(result ? [result] : [])
        })

        return promise
      }

      query.toArray = function () {
        var promise = query.__proto__.toArray.call(query)
        stack = new Error().stack
        promise.then(report)
        return promise
      }

      return query
    }
  }