MemoryStoreSortedMap

local MemoryStoreService = game:GetService("MemoryStoreService")

local myMap = MemoryStoreService:GetSortedMap("MySortedMap")

function printAllKeys(map)
	-- the initial lower bound is nil which means to start from the very first item
	local exclusiveLowerBound = nil

	-- this loop continues until the end of the map is reached
	while true do
		-- get up to a hundred items starting from the current lower bound
		local items = map:GetRangeAsync(Enum.SortDirection.Ascending, 100, exclusiveLowerBound)

		for _, item in ipairs(items) do
			print(item.key)
			print(item.sortKey)
		end

		-- if the call returned less than a hundred items it means we've reached the end of the map
		if #items < 100 then
			break
		end

		-- the last retrieved key is the exclusive lower bound for the next iteration
		exclusiveLowerBound = {}
		exclusiveLowerBound["key"] = items[#items].key
		exclusiveLowerBound["sortKey"] = items[#items].sortKey
	end
end

printAllKeys(myMap)

local MemoryStoreService = game:GetService("MemoryStoreService")
local map = MemoryStoreService:GetSortedMap("Leaderboard")
local Players = game:GetService("Players")

function updateLeaderboard(itemKey, killsToAdd, deathsToAdd)
	local success, newStats, newScore = pcall(function()
		return map:UpdateAsync(itemKey, function(playerStats, playerScore)
			playerStats = playerStats or { kills = 0, deaths = 0 }
			playerStats.kills += killsToAdd
			playerStats.deaths += deathsToAdd
			if playerStats then
				-- `playerScore` is the sortKey being used to sort items in the map
				playerScore = playerStats.kills / math.max(playerStats.deaths, 1)
				return playerStats, playerScore
			end
			return nil
		end, 30)
	end)
end

-- Add one kill to all players
for i, player in pairs(Players:GetPlayers()) do
	updateLeaderboard(player.UserId, 1, 0)
end
-- Add 5 kills and 1 death to player with userId 12345
updateLeaderboard(12345, 5, 1)