IB Computer Science Topic A.1.2 Transactions and Data Consistency Revision Notes (SL/HL)

IB Computer Science Topic A.1.2 Transactions and Data Consistency Revision Notes (SL/HL) | RevisionDojo

Definition

Database Transaction

A single unit of work, consisting of one or more (SQL) operations which are executed atomically such that all changes take effect together (commit) or none do (rollback).

Importance of ACID Properties in a Database Transaction

ACID is an acronym for: Atomicity, Consistency, Isolation, Durability.
All transactions must adhere to ACID principles, which are the following:
1. Atomicity is when all tasks in a transaction are performed (committed), or none are (rollback).
  1. This ensures there are no partial writes and corrupt data writes.
2. Consistency is where the data written must be valid according to existing rules.
3. Isolation indicates each transaction must not interfere with other transactions.
  1. This helps avoid data inconsistency among concurrent transactions.
4. Durability is the concept where when a transaction is committed, the change to the database is permanent, even if system failure occurs.

Example

Atomicity: A bank transfer where debit and credit must both succeed or both roll back.
Consistency: Foreign‑key prevents an order pointing to a non‑existent customer.
Isolation: Two shoppers don’t buy the last ticket twice.
Durability: After reboot, confirmed bookings are still there.

Using Transactions, States and Updates to Maintain Data Consistency (and Integrity)

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Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Definition

Database Transaction

A single unit of work, consisting of one or more (SQL) operations which are executed atomically such that all changes take effect together (commit) or none do (rollback).

Importance of ACID Properties in a Database Transaction

ACID is an acronym for: Atomicity, Consistency, Isolation, Durability.
All transactions must adhere to ACID principles, which are the following:
1. Atomicity is when all tasks in a transaction are performed (committed), or none are (rollback).
  1. This ensures there are no partial writes and corrupt data writes.
2. Consistency is where the data written must be valid according to existing rules.
3. Isolation indicates each transaction must not interfere with other transactions.
  1. This helps avoid data inconsistency among concurrent transactions.
4. Durability is the concept where when a transaction is committed, the change to the database is permanent, even if system failure occurs.

Example

Atomicity: A bank transfer where debit and credit must both succeed or both roll back.
Consistency: Foreign‑key prevents an order pointing to a non‑existent customer.
Isolation: Two shoppers don’t buy the last ticket twice.
Durability: After reboot, confirmed bookings are still there.

Using Transactions, States and Updates to Maintain Data Consistency (and Integrity)

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

1. System fundamentals2 subtopics

2. Computer organization1 subtopic

3. Networks1 subtopic

4. Computational thinking, problem-solving and programming3 subtopics

5. Abstract data structures (HL)1 subtopic

6. Resource management (HL)1 subtopic

7. Control (HL)1 subtopic

A. Databases4 subtopics

B. Modelling and simulation4 subtopics

C. Web science6 subtopics

D. Object-oriented programming (OOP)4 subtopics

IB Computer Science A.1.2 Transactions and Data Consistency Notes

1. System fundamentals2 subtopics

2. Computer organization1 subtopic

3. Networks1 subtopic

4. Computational thinking, problem-solving and programming3 subtopics

5. Abstract data structures (HL)1 subtopic

6. Resource management (HL)1 subtopic

7. Control (HL)1 subtopic

A. Databases4 subtopics

B. Modelling and simulation4 subtopics

C. Web science6 subtopics

D. Object-oriented programming (OOP)4 subtopics

Importance of ACID Properties in a Database Transaction

Using Transactions, States and Updates to Maintain Data Consistency (and Integrity)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Importance of ACID Properties in a Database Transaction

Using Transactions, States and Updates to Maintain Data Consistency (and Integrity)

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account