Document versioning in Elasticsearch - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the version number when indexing a document.

Elasticsearch

POST /my_index/_doc/1?version=[1]
{
  "name": "Alice"
}

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

A2

B0

C1

Dlatest

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 as the version number causes errors.

Using 'latest' is not a valid version number.

The version number must be set to the current version of the document, which starts at 1.

2fill in blank

medium

Complete the code to update a document only if the version matches.

Elasticsearch

POST /my_index/_doc/1/_update?version=[1]
{
  "doc": {"age": 30}
}

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

A2

B3

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using an outdated version number causes version conflicts.

Using 0 or 1 when the current version is 2 causes errors.

To update safely, specify the current version number, here 2.

3fill in blank

hard

Fix the error in the code to prevent version conflicts when deleting a document.

Elasticsearch

DELETE /my_index/_doc/1?version=[1]

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

A1

B0

Clatest

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or 'latest' causes version conflict errors.

Using an outdated version number causes the delete to fail.

The version must match the current document version, here 2, to avoid conflicts.

4fill in blank

hard

Fill both blanks to create a document with version control and refresh immediately.

Elasticsearch

PUT /my_index/_doc/2?version=[1]&refresh=[2]
{
  "title": "New Doc"
}

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

A1

Btrue

Cfalse

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Using version 2 for a new document causes conflicts.

Setting refresh to false delays document availability.

Use version 1 for a new document and set refresh to true to make it searchable immediately.

5fill in blank

hard

Fill all three blanks to update a document with version check, retry on conflict, and refresh.

Elasticsearch

POST /my_index/_doc/3/_update?version=[1]&retry_on_conflict=[2]&refresh=[3]
{
  "doc": {"status": "active"}
}

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

A3

B5

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong version numbers causes conflicts.

Not setting retry_on_conflict may cause update failures.

Setting refresh to false delays search availability.

Use the current version 3, retry 5 times on conflict, and refresh immediately.

Practice

1. What is the main purpose of document versioning in Elasticsearch?

easy

A. To compress documents for storage efficiency

B. To prevent update conflicts by ensuring updates apply only to the expected document version

C. To increase the speed of document retrieval

D. To create backups of documents automatically

Solution

1. Step 1: Understand document versioning concept

   Document versioning is used to avoid conflicts when multiple updates happen simultaneously.

2. Step 2: Identify the main purpose

   It ensures updates only apply if the document is at the expected version, preventing overwriting newer changes.

3. Final Answer:

   To prevent update conflicts by ensuring updates apply only to the expected document version -> Option B

4. Quick Check:

   Versioning prevents conflicts = C [OK]

Hint: Versioning avoids conflicting updates by checking document version [OK]

Common Mistakes:

• Thinking versioning speeds up retrieval
• Confusing versioning with backup creation
• Assuming versioning compresses data

2. Which of the following is the correct way to specify a version when updating a document in Elasticsearch?

easy

A. POST /index/_update/1?version=3 { "doc": {"field": "value"} }

B. POST /index/_update/1 { "doc": {"field": "value"}, "version_number": 3 }

C. POST /index/_update/1 { "doc": {"field": "value"}, "ver": 3 }

D. POST /index/_update/1 { "doc": {"field": "value"}, "version": 3 }

Solution

1. Step 1: Recall Elasticsearch update syntax with version

   The version parameter is passed as a query parameter, not inside the JSON body.

2. Step 2: Identify correct syntax

   POST /index/_update/1?version=3 { "doc": {"field": "value"} } uses ?version=3 in the URL, which is the correct way to specify version for update.

3. Final Answer:

   POST /index/_update/1?version=3 { "doc": {"field": "value"} } -> Option A

4. Quick Check:

   Version is a query parameter, not in body [OK]

Hint: Use ?version=number in URL, not inside JSON body [OK]

Common Mistakes:

• Putting version inside JSON body
• Using wrong parameter names like ver or version_number
• Omitting the version parameter

3. Given the following update request, what will happen if the current document version is 5?

POST /myindex/_update/42?version=4
{
  "doc": {"status": "active"}
}

medium

A. The update will succeed and document version will become 5

B. The update will succeed but version will remain 4

C. The update will fail due to version conflict

D. The update will create a new document with version 4

Solution

1. Step 1: Check the version parameter against current document version

   The update request specifies version=4 but current version is 5.

2. Step 2: Understand version conflict behavior

   Elasticsearch rejects updates if the version does not match the current document version to avoid conflicts.

3. Final Answer:

   The update will fail due to version conflict -> Option C

4. Quick Check:

   Version mismatch causes update failure [OK]

Hint: Update only succeeds if version matches current document version [OK]

Common Mistakes:

• Assuming update succeeds despite version mismatch
• Thinking version resets after update
• Confusing version with document ID

4. You wrote this update request but it always fails with a version conflict error:

POST /products/_update/10?version=2
{
  "doc": {"price": 19.99}
}

What is the most likely cause?

medium

A. The update syntax is incorrect

B. The document with ID 10 does not exist

C. The field name 'price' is invalid

D. The current document version is not 2

Solution

1. Step 1: Understand version conflict error meaning

   Version conflict means the version specified does not match the document's current version.

2. Step 2: Check other options

   Document existence or field name errors cause different errors; syntax is correct here.

3. Final Answer:

   The current document version is not 2 -> Option D

4. Quick Check:

   Version conflict means version mismatch [OK]

Hint: Version conflict means your version number is outdated [OK]

Common Mistakes:

• Assuming document absence causes version conflict
• Blaming field names for version errors
• Ignoring correct syntax

5. You want to update a document only if it has not been changed since you last read it. Which approach correctly uses document versioning to achieve this?

hard

A. Fetch the document, note its version, then update using that version parameter

B. Update the document without specifying any version parameter

C. Use the document ID as the version parameter in the update request

D. Delete the document first, then create a new one with the updated data

Solution

1. Step 1: Understand optimistic concurrency control

   You must check the document's current version before updating to avoid overwriting changes.

2. Step 2: Apply versioning correctly

   Fetch the document, get its version, then update specifying that version to ensure no changes happened in between.

3. Final Answer:

   Fetch the document, note its version, then update using that version parameter -> Option A

4. Quick Check:

   Use version to update only if unchanged [OK]

Hint: Always update with the version you last read to avoid conflicts [OK]

Common Mistakes:

• Updating without version check causes silent overwrites
• Using document ID as version parameter
• Deleting instead of updating