Index Modules are modules created per index and control all aspects related to an index.
Index level settings can be set per-index. Settings may be:
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:
- 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.
[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:
- (default) Don’t check for corruption when opening a shard.
- Check for physical corruption.
- Check for both physical and logical corruption. This is much more expensive in terms of CPU and memory usage.
- 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.
defaultvalue compresses stored data with LZ4 compression, but this can be set to
best_compressionwhich 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:
- The number of replicas each primary shard has. Defaults to 1.
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
allfor the upper bound (e.g.
0-all). Defaults to
How often to perform a refresh operation, which makes recent changes to the
index visible to search. Defaults to
1s. Can be set to
-1to disable refresh.
The maximum value of
from + sizefor searches to this index. Defaults to
10000. Search requests take heap memory and time proportional to
from + sizeand this limits that memory. See to raising this.
trueto make the index and index metadata read only,
falseto allow writes and metadata changes.
trueto disable read operations against the index.
trueto disable write operations against the index.
trueto disable index metadata reads and writes.
- [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.
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:
Number values are also supported, e.g.
Settings in other index modulesedit
Other index settings are available in index modules:
- Settings to define analyzers, tokenizers, token filters and character filters.
- Index shard allocation
- Control over where, when, and how shards are allocated to nodes.
- Enable or disable dynamic mapping for an index.
- Control over how shards are merged by the background merge process.
- Configure custom similarity settings to customize how search results are scored.
- Control over how slow queries and fetch requests are logged.
- Configure the type of filesystem used to access shard data.
- Control over the transaction log and background flush operations.