[eluser]Jelmer[/eluser]
I didn't mean my answer in a bad way, I was just genuinly surprised you'd want that.
In my opinion a thousand rows is too much for one page, being admin or not. Also I personally don't cache anything in the admin. Caching is for parts of the website that are frequently requested, possibly multiple times per second or even more. Caching the admin isn't worth the trouble in my opinion because those operations are incidental (server-load wise) and only for one or a few users.
And lastly, you can make mistakes implementing Cache. And when you're editing the database (as you probably are in the admin) you should always work on the real data, not the cached data to prevent miscommunications between you and the system.
I must admit I'm not aware on any limitation for the length of an array. You are limited in the amount of memory you're using, which could conceivibly stop you from using such gigantic arrays.
