elasticsearch/docs/reference/elasticsearch/index-settings/index.md

Index settings

$$$index-modules-settings-description$ Index level settings can be set per-index. Settings 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:

• History retention Control the retention of a history of operations in the index.
• Index General settings that affect the behavior of indices.
• Index shard allocation Control where, when, and how shards are allocated to nodes.
• Indexing pressure Configure indexing back pressure limits.
• 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.
• 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.

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