Fetching data from a database

I use mysql database for my coins plugin.. and i query "SELECT..." every time a player run /coins...

Is this a bad practice? What would be a better one?

 

how do i store in ram?

 

Cache the query result for as long as you think is a significant time.

You could write your code in an efficient way to deal with the problem of frequent database calls. But again, it all points back to cache manipulation.

 

Like caching into a json or txt file? Should I do this when the plugin enables?

 

You can query once and store it in a variable, update it when you change the value and save to db when player quits

 

a variable as in an array?

 

That's one way to do it, you can also create your own class and store it like sessions

 

I see... how about adding data to a variable when a player joins?

 

You can load it when player join or only when you need it, either one works

 

What if the server crash? Will it still save to db when players quit?

 

You can do that by saving all online players' data in onDisable and optionally do a check if server is running before saving if thats what you wanted

 

Then i guess the only way would be to save whenever there is a modification? Is there a better way?

 

should i use uuid or player's name as key?

 

Since names can be changed, I would choose the UUID or XUID because it is (usually) a unique identifier for a player.

 

OKay so right now I save players data from MySQL into memory on PlayerLoginEvent. Something worries me though... what if multiple players join simultaneously? Will MySQL be able to keep up with querying, and not let a player join the server without their data saved in the memory?

 

So I save data from mysql to an array right now.. should I unset the player from the array when they leave? I think I shouldn't so that when they join I won't have to query again. And when the server restarts, does the array get abandoned or cleared itself?