Document versioning in Elasticsearch - Step-by-Step Execution

Concept Flow - Document versioning

Start: Document Indexed

↓

Assign Version = 1

↓

Update Request Received

↓

Check Version in Request

↓

Update

↓

Increment Version

↓

Save Document

↓

End

When a document is first indexed, it gets version 1. On updates, Elasticsearch checks the version to avoid conflicts. If versions match, it updates and increments the version. If not, it rejects the update.

Execution Sample

Elasticsearch

PUT /my_index/_doc/1
{
  "name": "Alice"
}

PUT /my_index/_doc/1?if_seq_no=0&if_primary_term=1
{
  "name": "Alice Updated"
}

This code indexes a document with id 1, then updates it only if the version matches to avoid conflicts.

Execution Table

Step	Action	Version Before	Version Check	Result	Version After
1	Index new document id=1	N/A	N/A	Document created	1
2	Update document id=1 with if_seq_no=0 & if_primary_term=1	1	Matches current version	Update accepted	2
3	Update document id=1 with if_seq_no=0 & if_primary_term=1 again	2	Does not match current version	Update rejected	2

💡 Update rejected at step 3 because version check failed (conflict detected).

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3
Document Version	N/A	1	2	2

Key Moments - 2 Insights

Why does the update get rejected at step 3 even though the same version check is used?

Because after step 2, the document version incremented to 2. The update at step 3 still uses the old version (seq_no=0, primary_term=1), so the version check fails, causing rejection as shown in execution_table row 3.

What happens to the version number when a document is first indexed?

At step 1, the document is created with version 1, as shown in execution_table row 1 and variable_tracker.

Visual Quiz - 3 Questions

Look at the execution_table, what is the document version after step 2?

A 1

B 2

C 3

D 0

💡 Hint

Check the 'Version After' column in execution_table row 2.

At which step does the update get rejected due to version conflict?

A Step 1

B Step 2

C Step 3

D No rejection occurs

💡 Hint

Look at the 'Result' column in execution_table row 3.

If the update at step 3 used the correct current version, what would happen?

A Update would be accepted and version incremented

B Update would still be rejected

C Document would be deleted

D No change in version

💡 Hint

Refer to the behavior shown in execution_table row 2 where version matched and update succeeded.

Concept Snapshot

Document versioning in Elasticsearch:
- New documents start at version 1
- Updates require matching version (seq_no & primary_term)
- If versions match, update succeeds and version increments
- If versions mismatch, update is rejected to avoid conflicts
- Helps keep data consistent in concurrent environments

Full Transcript

Document versioning in Elasticsearch helps keep data consistent. When you add a new document, it starts with version 1. When you update it, Elasticsearch checks if your update matches the current version. If it does, the update happens and the version number goes up by one. If it doesn't match, the update is rejected to avoid overwriting changes made by others. This way, Elasticsearch prevents conflicts and keeps your data safe.