create procedure sys.sp_MSlevelchanges @gen bigint, @art_nick int, @leveling_threshold int, @nickbin varbinary(255), @replnick binary(6), @level_deletes_only bit = 0, @force_leveling bit = 0 output as
begin
    declare @num_changes_total int
    , @cur_contents_nickname int
    , @cur_tombstone_nickname int
    , @cur_change_count int
    , @newgen bigint
    , @genguid uniqueidentifier
    , @dt datetime
    , @making_tombstone_progress bit
    , @making_contents_progress bit
    , @retcode int
    , @changecount int
    , @remaining_count int
    , @running_total int

    if @leveling_threshold is null
        select @leveling_threshold = 1000    -- Default is 1000. We don't have to be accurate about this threshold, so counting changes
                                            -- with nolock should be okay.
    else if @leveling_threshold = 0
        return 0                            -- No need to do any leveling. Gens can be of infinite size.
    else if @leveling_threshold < 0
        return 0

    if @level_deletes_only  = 0
    begin
        select @num_changes_total = (select count(*) from dbo.MSmerge_contents with (nolock) where generation = @gen)
                                + (select count(*) from dbo.MSmerge_tombstone with (nolock) where generation = @gen)
    end
    else
    begin
        select @num_changes_total = (select count(*) from dbo.MSmerge_tombstone with (nolock) where generation = @gen)
    end

    if @num_changes_total <= @leveling_threshold and @force_leveling = 0
        return 0

    set @making_tombstone_progress = 1
    if @level_deletes_only = 0
        set @making_contents_progress = 1
    else
        set @making_contents_progress = 0
    set @running_total = 0
    set @cur_change_count = 0

    while @making_tombstone_progress = 1 or @making_contents_progress = 1
    begin

        select @running_total = @running_total + @cur_change_count

        select @genguid = newid(), @dt = getdate()

        insert into dbo.MSmerge_genhistory with (rowlock)
            (guidsrc, genstatus, art_nick, nicknames, coldate)
            values (@genguid, 0, @art_nick, @nickbin, @dt)
        if (@@error <> 0)
        begin
            return 1
        end
        select @newgen = @@identity

        select @cur_change_count = 0

        -- the threshold is just a guideline, not something we have to follow accurately at all costs.
        while @cur_change_count < @leveling_threshold and @making_tombstone_progress = 1
        begin
            set @cur_tombstone_nickname = NULL
            set @making_tombstone_progress = 0

            -- let us level the tombstones first, so that they get the lower generations.
            if isnull(@art_nick, 0) = 0
            begin
                select top 1 @cur_tombstone_nickname = mt.tablenick
                from dbo.MSmerge_tombstone mt with (nolock), dbo.sysmergearticles sma
                where mt.generation = @gen
                and mt.tablenick = sma.nickname
                order by sma.processing_order desc, sma.nickname desc
            end
            else
            begin
                select top 1 @cur_tombstone_nickname = mt.tablenick
                from dbo.MSmerge_tombstone mt with (nolock)
                where mt.generation = @gen
                and mt.tablenick = @art_nick
            end

            if @cur_tombstone_nickname is null
                break

            select @remaining_count = @leveling_threshold - @cur_change_count

            update top (@remaining_count) dbo.MSmerge_tombstone set generation = @newgen
            where generation = @gen and tablenick = @cur_tombstone_nickname

            select @cur_change_count = @@rowcount + @cur_change_count

            update ppm set generation = @newgen
            from dbo.MSmerge_past_partition_mappings ppm inner join dbo.MSmerge_tombstone ts
            on ppm.tablenick = ts.tablenick
            and ppm.rowguid = ts.rowguid
            and ts.generation = @newgen
            and ppm.generation = @gen
            and ppm.tablenick = @cur_tombstone_nickname
            and ts.tablenick = @cur_tombstone_nickname

            set @making_tombstone_progress = 1
        end

        while @cur_change_count < @leveling_threshold and @making_contents_progress = 1
                                                                and @making_tombstone_progress = 0
                                                                and @level_deletes_only = 0
        begin
            set @cur_contents_nickname = NULL
            set @making_contents_progress = 0

            -- now let us level the contents rows.
            if isnull(@art_nick, 0) = 0
            begin
                select top 1 @cur_contents_nickname = mc.tablenick
                from dbo.MSmerge_contents mc with (nolock), dbo.sysmergearticles sma
                where mc.generation = @gen
                and mc.tablenick = sma.nickname
                order by sma.processing_order, sma.nickname
            end
            else
            begin
                select top 1 @cur_contents_nickname = mc.tablenick
                from dbo.MSmerge_contents mc with (nolock)
                where mc.generation = @gen
                and mc.tablenick = @art_nick
            end

            if @cur_contents_nickname is null
                break

            select @remaining_count = @leveling_threshold - @cur_change_count

            update top (@remaining_count) dbo.MSmerge_contents set generation = @newgen
            where generation = @gen and tablenick = @cur_contents_nickname

            select @cur_change_count = @@rowcount + @cur_change_count

            set @making_contents_progress = 1
        end
        if @cur_change_count = 0
        begin
            delete from dbo.MSmerge_genhistory with (rowlock) where generation = @newgen
        end
        else
        begin
            select @force_leveling = 1 -- from now on all subsequent generations will be forced to level to
                                        -- minimize DRI violations.
            exec @retcode = sys.sp_MSclosegeneration @newgen, @art_nick, @genguid, @replnick
            if @retcode <> 0 or @@error <> 0
            begin
                return 1
            end
        end
    end

    return 0
end