             delete @_requestersByQs[deletedQss][computation._id]
             if _.isEmpty @_requestersByQs[deletedQss]
                 delete @_requestersByQs[deletedQss]
+                @_incChanges @parseQs(deletedQss).modelName, deletedQss, -1
                 requestsChanged = true
 
         delete @_qsByRequester[computation._id]

        for addedQss in qsStringsDiff.added
            if addedQss not of @_requestersByQs
                @_requestersByQs[addedQss] = {}
                requestsChanged = true
            @_requestersByQs[addedQss][computation._id] = computation




_.extend J.fetching,
    _incChanges: (modelName, qss, inc) ->
        @_changesByModelQs[modelName] ?= {}
        newValue = (@_changesByModelQs[modelName][qss] ? 0) + inc
        if newValue is 0
            delete @_changesByModelQs[modelName][qss]
        else
            @_changesByModelQs[modelName][qss] = newValue

    _addComputationQsRequest: (computation, qs) ->
        qsString = @stringifyQs qs

