Write concern levels (w: 1, majority) in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set write concern to acknowledge writes by the primary only.

MongoDB

db.collection.insertOne({name: "Alice"}, {writeConcern: {w: [1])

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A0

Ball

Cmajority

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 means no acknowledgment.

Using 'majority' waits for more nodes.

Setting w: 1 means the write is acknowledged by the primary only.

2fill in blank

medium

Complete the code to set write concern to wait for majority of nodes to acknowledge.

MongoDB

db.collection.updateOne({_id: 1}, {$set: {score: 100}}, {writeConcern: {w: [1])

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A1

B0

Cmajority

Dall

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 waits only for primary.

Using 0 means no acknowledgment.

Using w: 'majority' waits for most nodes to confirm the write.

3fill in blank

hard

Fix the error in the write concern option to correctly wait for majority acknowledgment.

MongoDB

db.collection.deleteOne({_id: 5}, {writeConcern: {w: [1])

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Amajority

B1

CMajority

Dall

Attempts:

3 left

💡 Hint

Common Mistakes

Using capitalized 'Majority' causes error.

Using numeric values won't wait for majority.

The write concern value 'majority' must be lowercase string exactly.

4fill in blank

hard

Fill both blanks to set write concern to acknowledge by primary and timeout after 5000ms.

MongoDB

db.collection.insertMany(docs, {writeConcern: {w: [1], wtimeout: [2])

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A1

Bmajority

C5000

D1000

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'majority' with a low timeout may cause errors.

Using 0 for w means no acknowledgment.

Setting w: 1 waits for primary acknowledgment and wtimeout: 5000 sets 5 seconds timeout.

5fill in blank

hard

Fill all three blanks to set write concern to majority, timeout 2000ms, and journal enabled.

MongoDB

db.collection.updateMany(filter, update, {writeConcern: {w: [1], wtimeout: [2], j: [3])

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A1

B2000

CTrue

Dmajority

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'true' as string instead of boolean.

Using 0 for w disables acknowledgment.

Using w: 'majority' waits for majority, wtimeout: 2000 sets 2 seconds timeout, and j: true enables journaling.