Concerns about Berezaa's datastore saving method

Kampfkarren · August 8, 2018, 9:06pm

DataStore2 does this.

Kampfkarren/Roblox/blob/master/DataStore2.module.lua#L412


	return self.backup ~= nil --some people haven't learned if x then yet, and will do if x == false then.
end


--[[**
	<description>
	Saves the data to the data store. Called when a player leaves.
	</description>
**--]]
function DataStore:Save()
	if not self.valueUpdated then
		warn(("Data store %s was not saved as it was not updated."):format(self.name))
		return
	end
	
	if game:GetService("RunService"):IsStudio() and not SaveInStudio then
		warn(("Data store %s attempted to save in studio while SaveInStudio is false."):format(self.name))
		if not SaveInStudioObject then
			warn("You can set the value of this by creating a BoolValue named SaveInStudio in ServerStorage.")
		end
		return
	end

sleitnick · September 17, 2018, 11:53pm

Just gotta watch out for table changes. If you are saving tables, then that means that the values inside the table are changing, and not the actual table itself, thus could be marked as ‘clean’ still and not get saved. I ran into this issue with my DataStore system.

Kampfkarren · September 17, 2018, 11:54pm

Call it a hack, but DataStore2 always deep copies tables before setting/getting to stop this exact oversight.

github.com

Kampfkarren/Roblox/blob/master/DataStore2.module.lua#L220


	
	local value
	
	if self.value == nil and defaultValue ~= nil then --not using "not" because false is a possible value
		value = defaultValue
	else
		value = self.value
	end
	
	if typeof(value) == "table" then
		value = table.deep(value)
	end
	
	self.value = value
	
	return value
end


--[[**
	<description>
	The same as :Get only it'll check to make sure all keys in the default data provided

github.com

Kampfkarren/Roblox/blob/master/DataStore2.module.lua#L277


	<description>
	Sets the cached result to the value provided
	</description>
	
	<parameter name = "value">
	The value
	</parameter>
**--]]
function DataStore:Set(value)
	if typeof(value) == "table" then
		self.value = table.deep(value)
	else
		self.value = value
	end
	
	self:_Update()
end


--[[**
	<description>
	Calls the function provided and sets the cached result.

This forces you to call :Set if you change the table.

Wunder_Wulfe · September 18, 2018, 1:09am

Periodical autosaving isnt required and it only prevents data loss when the datastores crash. Traditional bind to leave and bind to close saving should work almost all the time as long as connection maintained.

berezaa · September 18, 2018, 1:57am

2022 Edit: It’s impossible to completely prevent all data loss. Fortunately, the reliability and resiliency of the Roblox Datastore backend has improved considerably since that post was originally made. Along with saving when a player exits the game, it’s a good idea to periodically autosave the players data. You can further mitigate damage by warning the player when their autosave has failed.

Datastores have a massive outage almost every weekend. You cannot rely on bind to close for data, ever.

QuinnMcChief · May 25, 2023, 4:47pm

Is it only big games that get hit by these massive outages? Because I 100% guarantee after setting up a pcall function using GetAsync inside a repeat loop that runs 7 times before giving up, I haven’t had a single case of data loss—and one of the first order of operations for any game I make is creating a Datastore module (nothing special, just using GetAsync & SetAsync) but then again, I don’t have a huge game that has to handle hundreds of thousands of players.