python versus node for stateful upserting

node upserter

/**
 * postgres does not have replace into, so...
 *
 * @param {Object} tile specification {tx: ty: zoom:}
 * @param {Object} quad properties of that tile
 * @param {Knex.transaction} t database transaction
 * @return {Promise}
 */
function insertOrUpdateTile(tile, quad, t) {
  return db('tile').transacting(t).where(tile).count('*').then(
    function(result) {
      var count = parseInt(result[0].aggregate, 10);
      if (count === 0) {
        var tileRecord = merge(true, tile, quad);
        return db('tile').transacting(t).insert(tileRecord);
      } else if (count === 1) {
        return db('tile').transacting(t).where(tile).update(quad);
      } else {
        throw 'unexpected database count = ' + count + ' result for tile ' + JSON.stringify(tile) + '; should be 0 or 1';
      }
    }
  );
}


function quadLoop(pairs) {
  console.log("  quadLoop", pairs.length);
  return db.transaction(function(t) {
    return promiseForEach(pairs, function(pair) {
      var quadId = pair[0];
      var quad = pair[1];
      var tile = mt.getTileFromQuadTreePath(quadId);
      return insertOrUpdateTile(tile, quad, t);
    }).then(t.commit, t.rollback);
  });
}

/**
 * @param {Object} results array of zoomlevels, each zoomlevel is a dictionary of quadTreePaths (ids) to properties
 * @return {Promise}
 */
function writeResultsToDb(results) {
  // results is an array of zoom levels, in each zoom level is a hash of quadtreeid -> { various props, with same names as db columns }
  // we need to turn each of those into a record, then insert or update them
  console.log("---> write results to db");

  var doZoomDict = function (zoomDict) {
    var pairs = getKeyValPairs(zoomDict);
    console.log("pairs", pairs.length);
    var pairsGrouped = groupArray(pairs, UPSERTS_PER_TRANSACTION);
    return promiseForEach(pairsGrouped, quadLoop);
  };

  // filtering out false values (empty zoomlevels) because promiseWhile terminates on false
  results = results.filter(function(el) { return el; });

  return promiseForEach(results, doZoomDict, "doZoomDict");
}

python upserter

def upsertZooms(Session, zooms):
    for zoom in zooms:
        if zoom == None:
            continue

        session = Session()
        db = Db(session)
        count = 0
        print len(zoom.items())
        for quadId, quad in zoom.items():
            upsertQuad(db, quadId, quad)
            if count > 0 and count % MAX_UPSERTS_PER_COMMIT == 0:
                session.commit()
            count += 1
        session.commit()

def upsertQuad(db, quadId, newQuadProps):
    (tx, ty, zoom) = getTileFromQuadTreePath(quadId)
    quad = db.getQuad(tx, ty, zoom)
    if quad is None:
        db.insertQuad(tx, ty, zoom, newQuadProps)
    else:
        db.updateQuad(tx, ty, zoom, newQuadProps)