What is a storage cell?

Question

Somewhat noob question:

I see the term storage cell talked about a lot on here (mostly regarding Mapping and Lazy), however I cannot find any documentation about it.

What exactly is a storage cell? Are they a set size? If so what is the size? Does the size vary based on individual pallet implementation? Is there any way to access the size of a storage cell in ink? What happens if a storage cell's size is exceeded? Is the data split across two cells instead?

I assume a storage cell is a record in a database on a node, is that correct?

Assuming storage costs are proportional to the number of records used in the db by a smart contract, it would be handy to know the size of the storage cells so I can optimise the smart contract storage accordingly.

Answer 1

TLDR: ink! storage documentation

To answer your questions:

Storage in ink! is organized as a key/value database. So for each unique key, you have one unique cell (which can contain a value). The values are SCALE encoded, and the maximum length of a value is defined by the pallet. If this value is exceeded, you will get a DispatchError, and the contract execution will be trapped (reverted). The default value in substrate/frame/contracts is 16 * 1024 bytes.