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Index settings

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Settings supported in Serverless

Elastic Cloud Serverless projects restrict the available Elasticsearch settings to a supported subset, identified with a Serverless badge next to the setting name. For a complete list of available index settings, refer to the Serverless index settings list.

Elasticsearch organizes index-level settings into index modules, each controlling a specific aspect of index behavior.

These settings are configured on a per-index basis and may be:

  • Static They can only be set at index creation time or on a closed index, or by using the update index settings API with the reopen query parameter set to true (which automatically closes and reopens impacted indices).
  • Dynamic They can be changed on a live index using the update index settings API.
Warning

You can change any documented index settings on closed indices. However, changing undocumented index settings on closed indices is unsupported and might result in errors.

Settings are available for the following modules:

  • General: Index settings not tied to a specific module.
  • Index shard allocation: Control where, when, and how shards are allocated to nodes.
  • History retention Control how long the history of operations is retained in the index.
  • Index blocks: Block different type of operations to the indices.
  • Mapping limits: Limit the number of field mappings.
  • Merge: Control how shards are merged by the background merge process.
  • Similarities: Configure custom similarity settings to customize how search results are scored.
  • Slowlog: Control how slow queries and fetch requests are logged.
  • Sorting: Configure how to sort the segments inside each shard.
  • Store: Configure the type of filesystem used to access shard data.
  • Time series Configure the backing indices in a time series data stream (TSDS).
  • Translog Control the transaction log and background flush operations.
  • Indexing pressure Configure indexing back pressure limits.

There are also index settings associated with text analysis, which define analyzers, tokenizers, token filters, and character filters.