The index.codec setting in Elasticsearch controls the compression algorithm used for storing data within an index. This setting affects how efficiently data is stored on disk and can impact both storage requirements and query performance.
- Default value:
"default"(which uses LZ4 compression) - Possible values:
"default","best_compression","none" - Recommendations: Use the default setting unless you have specific requirements for increased compression or faster performance.
The index.codec setting determines the trade-off between storage efficiency and query performance. The "default" codec provides a good balance, while "best_compression" offers better storage efficiency at the cost of slower compression and decompression speeds.
Example
To set the index codec to "best_compression" when creating a new index:
PUT /my_index
{
"settings": {
"index": {
"codec": "best_compression"
}
}
}
You might want to change this setting if you need to optimize for storage space and are willing to accept slightly slower query performance. This can be particularly useful for indices with infrequently accessed historical data.
Common Issues and Misuses
- Changing the codec for an existing index requires reindexing, which can be resource-intensive for large datasets.
- Using
"best_compression"on frequently accessed indices may lead to decreased query performance. - Setting
"none"eliminates compression, which can significantly increase storage requirements and is rarely recommended.
Do's and Don'ts
Do:
- Use
"best_compression"for indices with infrequently accessed data to save storage space. - Consider the trade-off between storage efficiency and query performance when choosing a codec.
- Test different codecs in a non-production environment to measure their impact on your specific use case.
Don't:
- Change the codec frequently, as it requires reindexing.
- Use
"none"unless you have a very specific reason and understand the storage implications. - Assume that
"best_compression"is always the best choice; it depends on your use case and performance requirements.
Frequently Asked Questions
Q: Can I change the index.codec setting for an existing index?
A: No, changing the codec requires reindexing. You'll need to create a new index with the desired codec and reindex your data into it.
Q: How much storage space can I save by using "best_compression"?
A: The storage savings can vary depending on your data, but typically you can expect to save around 20-30% more space compared to the default LZ4 compression.
Q: Will using "best_compression" significantly impact my query performance?
A: While there is some impact on query performance due to increased decompression time, the difference is often negligible for most use cases. However, it's best to test with your specific workload.
Q: Is it possible to use different codecs for different fields within the same index?
A: No, the index.codec setting applies to the entire index. You cannot specify different codecs for individual fields.
Q: How does the index.codec setting interact with other compression settings in Elasticsearch?
A: The index.codec setting is separate from other compression settings like _source compression. It specifically affects how the inverted index and stored fields are compressed on disk.
