Gas optimization with storage in Blockchain / Solidity - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is 'gas' in blockchain smart contracts?

Gas is the fee required to perform operations on a blockchain like Ethereum. It measures the computational effort needed to execute transactions or smart contracts.

beginner

Why is storage expensive in smart contracts?

Storing data on the blockchain uses permanent space and requires more gas because it affects all nodes. Reading and writing storage costs more gas than using temporary memory.

intermediate

How can packing variables reduce gas costs?

Packing multiple smaller variables into a single storage slot reduces the number of storage slots used, lowering gas costs because fewer storage operations are needed.

intermediate

What is the benefit of using 'calldata' instead of 'memory' for function parameters?

Using 'calldata' for external function parameters avoids copying data into memory, saving gas because calldata is read-only and cheaper to access.

beginner

Explain why minimizing storage writes saves gas.

Each write to storage costs a lot of gas. Minimizing writes by updating storage only when necessary or batching changes reduces gas consumption significantly.

Which operation generally costs the most gas in a smart contract?

A Writing data to storage

B Reading data from memory

C Calling a view function

D Using local variables

Writing data to storage is the most expensive operation because it permanently changes the blockchain state.

What does 'packing variables' mean in gas optimization?

A Combining multiple small variables into one storage slot

B Compressing data before storing

C Using fewer functions

D Storing variables in memory instead of storage

Packing variables means placing multiple small variables into a single 32-byte storage slot to reduce storage usage.

Why is 'calldata' cheaper than 'memory' for function inputs?

A Calldata uses less gas to write

B Calldata is stored off-chain

C Memory is slower to access

D Calldata is read-only and does not require copying

Calldata is cheaper because it is read-only and does not require copying data into memory.

Which of these reduces gas cost when updating storage?

A Writing to storage multiple times separately

B Using global variables instead of local

C Batching multiple updates into one transaction

D Avoiding function modifiers

Batching updates reduces the number of storage writes, saving gas.

What is a common practice to save gas when dealing with boolean variables?

A Store booleans in memory only

B Pack multiple booleans into one byte

C Convert booleans to strings

D Use separate storage slots for each boolean

Packing multiple booleans into one byte reduces storage slots used and saves gas.

Describe three ways to optimize gas costs related to storage in smart contracts.

Think about how data is stored and accessed in smart contracts.

Explain why storage operations are more expensive than memory operations in blockchain smart contracts.

Consider the difference between temporary and permanent data.