The following are two other settings related to performance, which are also commonly used in the _aliases API:
- Routing: A document is routed to a particular shard to store or search. Elasticsearch has a simple formula to calculate the route. However, users can customize their routing method. This feature can be used together with filtering aliases in order to avoid unnecessary shard operations. You can specify the parameter routing value according to your design when the index alias is created.
- Write index flag: If an alias points to multiple indices, a question will arise. Which index will take the write operations, such as indexing or updating? To resolve this issue, the is_write_index flag must be associated with one of ...