# Swap Indexes API

# 1. Summary

The swap indexes API allows to atomically deploy several new versions of indexes without any downtime for the search clients.

# 2. Motivation

It's critical to deploy a new version of an index without any downtimes to the search clients. This capability improves the development experience by allowing Meilisearch to better fit into their workflow.

# 3. Functional Specification

# 3.1. 0 downtime deployment workflow

A 0 downtime deployment looks like this:

  1. Search clients search on indexA.
  2. The developer builds a new index indexB representing the new index version to deploy to the search clients.
  3. When indexB is built and ready to be deployed, the developer sends an indexes swap request to Meilisearch for indexA and indexB.
  4. indexB documents, settings and tasks are swapped with indexA.
  5. Search clients search on the updated indexA without experiencing any downtime.

# 3.2. Deploying Multiple New Indexes Versions

The swap API supports multiple swap operations in an atomic fashion.

This means that for a search experience built using multiple indexes, Meilisearch is able to deploy all changes at once and thus clients will access the new version of all indexes at once without any downtime.

There is no need to deploy each new version of indexes one by one.

# 3.3. Enqueued Tasks After A Swap Operation Creation

Tasks enqueued after an indexSwap task creation date do not have their indexUid modified when the indexSwap will succeed. That is, if they are enqueued on indexA, they will run on the new version of indexA.

# 3.4. API Endpoints Definition

# 3.4.1. POST - /swap-indexes

Send one or many indexes swap operation at once.

# Payload definition

The payload body expects an array of JSON objects representing swap operations.

        "indexes": ["indexA", "indexA_new"]
        "indexes": ["indexB", "indexB_new"]

πŸ’‘ In the given example, two swap operations will occur at the same time and atomically.

indexA data will be swapped with indexA_new data while indexB data will be swapped with indexB_new data.

Sending [] is considered valid. No swap transactions will be performed.

# Swap Object Definition
Field Type Required
indexes Array of string representing indexUids True
# indexes
  • Type: Array of string
  • Required: True

Determines which two indexes should exchange their data for their given swap object.

# Response Definition

When the request is in a successful state, Meilisearch returns the HTTP code 202 Accepted. The response's content is the summarized representation of the received asynchronous task.

    "taskUid": 1,
    "indexUid": null,
    "status": "enqueued",
    "type": "indexSwap",
    "enqueuedAt": "2021-08-12T10:00:00.000000Z"

An indexSwap task is considered a global task; thus indexUid is null.

See Summarized task Object for 202 Accepted.

# Errors
# Synchronous Errors
  • πŸ”΄ If the instance is secured by a master key, accessing this route without the Authorization header returns a missing_authorization_header error.
  • πŸ”΄ If the instance is secured by a master key, accessing this route with a key that does not have permissions (missing indexes.swap action or having a value for the indexes field of a swap operation not being defined in the API Key indexes array) (i.e. other than the master key) returns anΒ invalid_api_keyΒ error.
  • πŸ”΄ Omitting Content-Type header returns a missing_content_type error.
  • πŸ”΄ Sending an empty Content-Type returns an invalid_content_type error.
  • πŸ”΄ Sending a different Content-Type than application/json returns an invalid_content_type error.
  • πŸ”΄ Sending an empty payload returns a missing_payload error.
  • πŸ”΄ Sending an invalid JSON payload returns a malformed_payload error.
  • πŸ”΄ Omitting the indexes array in a swap payload returns a missing_swap_indexes error.
  • πŸ”΄ Sending an indexes array containing an invalid index uid format returns an invalid_swap_indexes error.
  • πŸ”΄ Sending an indexes array not containing exactly 2 indexUids for a swap operation object returns a invalid_swap_indexes error.
  • πŸ”΄ Sending an indexUid more than once in the request payload returns a invalid_swap_duplicate_index_found error.
# Asynchronous Errors
  • πŸ”΄ Sending indexUids that do not exist within the indexes field of a swap operation returns an index_not_found error.

# 4. Technical Details

# 4.1. Swapping Data

When indexes are swapped their data is exchanged. It concerns:

  • The documents
  • The settings
  • The tasks history
    • An index swap between index_a and index_b will also replace every mention of index_a by index_b (and vice-versa) in the task history. Enqueued tasks are left unmodified.

# 5. Future Possibilities

  • Introduce a way to delete one of the swapped indexes when the swap operation occurs.