         { @bucketSource } = options
         currentBucketSyncState = 0
         lastBucketSyncState = 0
+        @toFetch = 0
 
     useBuckets: (start, end) ->
         [ isLower, definite ] = @bucketCache.isCountLower(start, end, @histogramThreshold)

        return [ticks, resolution];

    isSyncing: () ->
        return !(@lastSyncState is @currentSyncState) || !(@currentBucketSyncState is @lastBucketSyncState)

    doFetch: (start, end, params) ->
        # TODO: if below threshold -> do the usual fetching
        { scales } = params
        [ ticks, resolution ] = @makeTicks(scales.x)


                b = new Date(bucket.getTime() + (dt or resolution))
                source(a, b, params, (count) =>
                    @bucketCache.setBucket(resolution, a, dt, count)
                    @toFetch -= 1
                    @listeners.synced()
                    summaryCallback()
                )
