Transaction handling in GraphQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a transaction in database terms?

A transaction is a group of operations performed as a single unit. All operations must complete successfully, or none are applied, to keep data correct.

intermediate

What does ACID stand for in transaction handling?

ACID means Atomicity, Consistency, Isolation, and Durability. These are rules to make sure transactions work safely and correctly.

intermediate

Why is isolation important in transactions?

Isolation keeps transactions separate so they don't interfere with each other. This avoids problems like reading wrong or partial data.

beginner

What happens if a transaction fails during execution?

If a transaction fails, all changes made during it are undone (rolled back) so the database stays correct and unchanged.

advanced

How do you start and end a transaction in GraphQL with a database?

You start a transaction by telling the database to begin, then run your operations, and finally commit to save or rollback to undo if errors happen.

What does the 'Atomicity' property ensure in a transaction?

A All parts of the transaction succeed or none do

B Data is always consistent after transaction

C Transactions run at the same time without interference

D Changes are saved permanently

Atomicity means the transaction is all or nothing: either all steps succeed or none are applied.

Which of the following is NOT part of ACID properties?

A Atomicity

B Consistency

C Isolation

D Indexing

Indexing is a database optimization, not an ACID property.

What does 'rollback' do in transaction handling?

A Undoes all changes made in the transaction

B Starts a new transaction

C Saves all changes permanently

D Locks the database

Rollback reverses all changes made during the transaction to keep data safe.

Why is isolation important when multiple transactions run at the same time?

A To speed up the database

B To allow partial data reads

C To prevent transactions from interfering with each other

D To save memory

Isolation keeps transactions separate so they don't affect each other's data.

In GraphQL, how do you ensure multiple database operations are treated as one transaction?

A By using a single query

B By starting a transaction, running operations, then committing or rolling back

C By running operations in parallel

D By using multiple mutations without control

You explicitly start a transaction, perform operations, then commit or rollback to keep data consistent.

Explain the ACID properties and why they matter in transaction handling.

Think about how each property helps keep data correct and reliable.

Describe the steps to handle a transaction in a GraphQL API connected to a database.

Consider how you control the database actions inside your GraphQL resolver.