Smart contract Storage

• This is where state variables are stored
• It is persistent between function calls and transactions
• It is a key-value mapping of 2²⁵⁶ keys; each value is 32 bytes long

State Variables Storage Layout

• One Astronomically large array
• Solidity generates code that saves variable values in their declaration order.
• Variable first was declared first, it’s stored in slot 0
• Items that need less than 32 bytes are packed together. See Rules

						contract Sample {
							uint first;    // storage slot 0
							uint second;   // storage slot 1
						}
					

Astronomically large array mental model

15 minute break

Lab