Index Modules edit

Index Modules are modules created per index and control all aspects related to an index. Since those modules lifecycle are tied to an index, all the relevant modules settings can be provided when creating an index (and it is actually the recommended way to configure an index).

Index Settingsedit

There are specific index level settings that are not associated with any specific module. These include:

index.compound_format

Should the compound file format be used (boolean setting). The compound format was created to reduce the number of open file handles when using file based storage. However, by default it is set to false as the non-compound format gives better performance. It is important that OS is configured to give Elasticsearch “enough” file handles. See the section called “File Descriptorsedit”.

Alternatively, compound_format can be set to a number between 0 and 1, where 0 means false, 1 means true and a number inbetween represents a percentage: if the merged segment is less than this percentage of the total index, then it is written in compound format, otherwise it is written in non-compound format.

index.compound_on_flush
Should a new segment (create by indexing, not by merging) be written in compound format or non-compound format? Defaults to true. This is a dynamic setting.
index.refresh_interval
A time setting controlling how often the refresh operation will be executed. Defaults to 1s. Can be set to -1 in order to disable it.
index.shard.check_on_startup
Should shard consistency be checked upon opening. When true, the shard will be checked, preventing it from being open in case some segments appear to be corrupted. When fix, the shard will also be checked but segments that were reported as corrupted will be automatically removed. Default value is false, which doesn’t check shards.
Note

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

Warning

Setting index.shard.check_on_startup to fix may result in data loss, use with caution.