Read concern and write concern in transactions in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a transaction with a read concern of 'majority'.

MongoDB

const session = client.startSession();
session.startTransaction({ readConcern: { level: '[1]' } });

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

Amajority

Blinearizable

Clocal

Davailable

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'local' which reads from the node's local data and may not be majority committed.

Using 'available' which is not a valid read concern level.

The read concern 'majority' ensures the transaction reads data that has been acknowledged by a majority of replica set members.

2fill in blank

medium

Complete the code to set the write concern to 'w: 1' in a transaction.

MongoDB

session.startTransaction({ writeConcern: { w: [1] } });

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Amajority

B0

C1

Dall

Attempts:

3 left

💡 Hint

Common Mistakes

Using '0' which means no acknowledgment.

Using 'all' which is not a valid write concern value.

Write concern 'w: 1' means the write must be acknowledged by the primary node only.

3fill in blank

hard

Fix the error in the transaction options to correctly specify read concern level.

MongoDB

session.startTransaction({ readConcern: { level: '[1]' } });

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

AmajorityLevel

BMAJORITY

Cmajor

Dmajority

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase letters which cause errors.

Using incomplete or incorrect words.

The read concern level must be exactly 'majority' in lowercase.

4fill in blank

hard

Fill both blanks to start a transaction with read concern 'snapshot' and write concern 'majority'.

MongoDB

session.startTransaction({ readConcern: { level: '[1]' }, writeConcern: { w: '[2]' } });

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

Asnapshot

Blocal

Cmajority

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing read concern levels that are not supported in transactions.

Using write concern values that are not strings.

Read concern 'snapshot' provides a consistent view of data during the transaction. Write concern 'majority' ensures writes are acknowledged by most nodes.

5fill in blank

hard

Fill all three blanks to start a transaction with read concern 'local', write concern '1', and specify a max commit time of 1000 milliseconds.

MongoDB

session.startTransaction({ readConcern: { level: '[1]' }, writeConcern: { w: '[2]' }, maxCommitTimeMS: [3] });

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

Amajority

B1

C1000

Dlocal

Attempts:

3 left

💡 Hint

Common Mistakes

Using string quotes around maxCommitTimeMS value.

Confusing read concern levels.

This transaction uses read concern 'local' for reading the node's data, write concern '1' for primary acknowledgment, and sets a max commit time of 1000 milliseconds to limit commit duration.