Memory and storage engine basics (WiredTiger) in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check the current storage engine in MongoDB.

MongoDB

db.serverStatus().storageEngine.[1]

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

Aversion

Bstatus

Cengine

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'version' instead of 'name' returns undefined.

Using 'engine' or 'status' are not valid fields here.

The name field shows the current storage engine used by MongoDB, such as WiredTiger.

2fill in blank

medium

Complete the command to enable the WiredTiger cache size to 2GB in the MongoDB configuration file.

MongoDB

storage:
  wiredTiger:
    engineConfig:
      cacheSizeGB: [1]

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

A2

B0.5

C4

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting cache size too low may reduce performance.

Using strings instead of numbers causes config errors.

Setting cacheSizeGB to 2 allocates 2 gigabytes of RAM for WiredTiger's cache.

3fill in blank

hard

Fix the error in the command to check WiredTiger statistics.

MongoDB

db.serverStatus().wiredTiger.[1]

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

Acache

Bstats

Cstatus

Dinfo

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'cache' returns only cache info, not full stats.

Using 'status' or 'info' are invalid fields.

The stats field contains detailed WiredTiger statistics like cache usage and page reads.

4fill in blank

hard

Fill both blanks to create a command that lists all collections using WiredTiger storage engine.

MongoDB

db.getCollectionInfos({storageEngine: [1]: [2])

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

Aname

B"WiredTiger"

Cengine

D"wiredTiger"

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'engine' or 'WiredTiger' as keys causes no results.

Using uppercase 'WiredTiger' as value is case sensitive and incorrect.

The name field inside storageEngine is matched against wiredTiger to filter collections using that engine.

5fill in blank

hard

Fill all three blanks to create a command that sets the WiredTiger journal commit interval to 100 milliseconds.

MongoDB

db.adminCommand({setParameter: 1, [1]: [2], [3]: 100})

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

AwiredTigerEngineRuntimeConfig

B"journalCompressor"

C"commitIntervalMs"

DjournalCommitInterval

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect parameter names causes command failure.

Not quoting keys properly causes syntax errors.

The wiredTigerEngineRuntimeConfig parameter accepts a string with runtime settings. Setting "commitIntervalMs" to journalCommitInterval of 100 sets the journal commit interval to 100 milliseconds.