Redis, LUA, execute Redis command in chunks

executeRedisCommandInChunks.lua

-- to avoid the problem with unpack ("too many results to unpack")
-- we can increase LUAI_MAXCSTACK in luaconf.h https://www.lua.org/source/5.1/luaconf.h.html
-- or execute the command with using table.unpack (https://www.lua.org/manual/5.1/manual.html#pdf-table.unpack) in chunks by specific length
-- table.merge - separated function to merge two tables
-- size of args should be >4000 (chunk length)
local executeRedisCommandInChunks = function (command, key, args)
    local results = {}
    local chunkResult = {}
    local args_len = #args
    -- chunk length (any positive value less then 8000)
    local chunk_len = 4000
    if (string.len(key)>0) then
        -- for commands with one key like HMGET/HMSET
        for i = 1, args_len, chunk_len do
            chunkResult = redis.call(command, key, unpack(args, i, math.min(i + chunk_len - 1, args_len)))
            results = table.merge(results,chunkResult)
        end
    else
        -- for commands like DEL/MGET/MSET/etc
        for i = 1, args_len, chunk_len do
            chunkResult = redis.call(command, unpack(args, i, math.min(i + chunk_len - 1, args_len)))
            results = table.merge(results,chunkResult)
        end
    end
    return results
end

useful links
https://github.com/antirez/redis/blob/b903145/deps/lua/src/luaconf.h#L439
http://rosettacode.org/wiki/Array_concatenation#Lua
http://stackoverflow.com/questions/1410862/concatenation-of-tables-in-lua
http://lua-users.org/wiki/CopyTable