Index Modules edit

Index Modules are modules created per index and control all aspects related to an index.

Index Settingsedit

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.
dynamic
They can be changed on a live index using the update-index-settings API.
Warning

Changing static or dynamic index settings on a closed index could result in incorrect settings that are impossible to rectify without deleting and recreating the index.

Static index settingsedit

Below is a list of all static index settings that are not associated with any specific index module:

index.number_of_shards
The number of primary shards that an index should have. Defaults to 5. This setting can only be set at index creation time. It cannot be changed on a closed index.
index.shard.check_on_startup

[experimental] This functionality is experimental and may be changed or removed completely in a future release. Whether or not shards should be checked for corruption before opening. When corruption is detected, it will prevent the shard from being opened. Accepts:

false
(default) Don’t check for corruption when opening a shard.
checksum
Check for physical corruption.
true
Check for both physical and logical corruption. This is much more expensive in terms of CPU and memory usage.
fix
Check for both physical and logical corruption. Segments that were reported as corrupted will be automatically removed. This option may result in data loss. Use with extreme caution!

Checking shards may take a lot of time on large indices.

index.codec
[experimental] This functionality is experimental and may be changed or removed completely in a future release. The default value compresses stored data with LZ4 compression, but this can be set to best_compression which uses DEFLATE for a higher compression ratio, at the expense of slower stored fields performance.

Dynamic index settingsedit

Below is a list of all dynamic index settings that are not associated with any specific index module:

index.number_of_replicas
The number of replicas each primary shard has. Defaults to 1.
index.auto_expand_replicas
Auto-expand the number of replicas based on the number of available nodes. Set to a dash delimited lower and upper bound (e.g. 0-5) or use all for the upper bound (e.g. 0-all). Defaults to false (i.e. disabled).
index.refresh_interval
How often to perform a refresh operation, which makes recent changes to the index visible to search. Defaults to 1s. Can be set to -1 to disable refresh.
index.max_result_window
The maximum value of from + size for searches to this index. Defaults to 10000. Search requests take heap memory and time proportional to from + size and this limits that memory. See to raising this.
index.blocks.read_only
Set to true to make the index and index metadata read only, false to allow writes and metadata changes.
index.blocks.read
Set to true to disable read operations against the index.
index.blocks.write
Set to true to disable write operations against the index.
index.blocks.metadata
Set to true to disable index metadata reads and writes.
index.ttl.disable_purge
[experimental] This functionality is experimental and may be changed or removed completely in a future release. Disables the purge of expired docs on the current index.
index.recovery.initial_shards

A primary shard is only recovered only if there are enough nodes available to allocate sufficient replicas to form a quorum. It can be set to:

  • quorum (default)
  • quorum-1 (or half)
  • full
  • full-1.
  • Number values are also supported, e.g. 1.

Settings in other index modulesedit

Other index settings are available in index modules:

Analysis
Settings to define analyzers, tokenizers, token filters and character filters.
Index shard allocation
Control over where, when, and how shards are allocated to nodes.
Mapping
Enable or disable dynamic mapping for an index.
Similarities
Configure custom similarity settings to customize how search results are scored.
Slowlog
Control over how slow queries and fetch requests are logged.
Store
Configure the type of filesystem used to access shard data.
Translog
Control over the transaction log and background flush operations.

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