Serializable isolation in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the transaction isolation level to serializable in PostgreSQL.

PostgreSQL

BEGIN TRANSACTION ISOLATION LEVEL [1];

Drag options to blanks, or click blank then click option'

Aserializable

Bread committed

Crepeatable read

Dread uncommitted

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'read committed' which is the default but less strict.

Confusing 'repeatable read' with 'serializable'.

The serializable isolation level ensures transactions are executed with the highest isolation, preventing phenomena like dirty reads, non-repeatable reads, and phantom reads.

2fill in blank

medium

Complete the code to start a transaction with serializable isolation level using the SET command.

PostgreSQL

SET TRANSACTION ISOLATION LEVEL [1];

Drag options to blanks, or click blank then click option'

Aserializable

Bread uncommitted

Crepeatable read

Dread committed

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'read uncommitted' which is not supported in PostgreSQL.

Using 'repeatable read' which is less strict than serializable.

Using SET TRANSACTION ISOLATION LEVEL serializable; sets the isolation level for the current transaction to serializable.

3fill in blank

hard

Fix the error in the code to correctly set the isolation level to serializable.

PostgreSQL

BEGIN TRANSACTION ISOLATION [1];

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Aserializable level

Blevel serializable

Cserializable

Disolation level serializable

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the word 'LEVEL' after 'ISOLATION'.

Swapping the order of 'serializable' and 'level'.

The correct syntax is BEGIN TRANSACTION ISOLATION LEVEL serializable;. The original code misses 'LEVEL serializable' after 'ISOLATION', so {{BLANK_1}} should be filled with 'level serializable' (SQL keywords are case-insensitive).

4fill in blank

hard

Fill both blanks to write a query that sets the isolation level to serializable and starts a transaction.

PostgreSQL

[1] TRANSACTION ISOLATION [2] serializable;

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ABEGIN

BCOMMIT

CLEVEL

DROLLBACK

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'COMMIT' or 'ROLLBACK' to start a transaction.

Omitting the 'LEVEL' keyword.

The correct syntax to start a transaction with serializable isolation is BEGIN TRANSACTION ISOLATION LEVEL serializable;. Here, the blanks are for 'BEGIN' and 'LEVEL'.

5fill in blank

hard

Fill all three blanks to write a transaction block that sets serializable isolation, inserts a row, and commits.

PostgreSQL

[1] TRANSACTION ISOLATION LEVEL serializable;
INSERT INTO accounts (id, balance) VALUES (1, 1000);
[2];

Drag options to blanks, or click blank then click option'

ABEGIN

BCOMMIT

CROLLBACK

DSTART

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'START' instead of 'BEGIN'.

Using 'ROLLBACK' instead of 'COMMIT'.

The transaction starts with BEGIN and ends with COMMIT to save changes. 'ROLLBACK' would undo changes, and 'START' is not a valid command here.