There has been a recurring ask to be able to prioritize some queries over other queries. One use-case for this feature is the ability to run user queries and system queries on the same cluster. Some ideas have been suggested like having separate threadpools or using priority queues rather than regular queues. Regardless of priority, search requests are competing for the same resources in the end, so given that we don't have (and probably don't want) the ability to pause running queries, low-priority queries would likely always have the potential to slow down higher-priority queries.

This doesn't mean that we shouldn't do anything, hence this new issue where we would like to collect feedback about use-cases to see what we could do. Please share your use-case, we are especially interested to know:

• How would you decide on the priority of a request?
• How many priorities you would need? (only 2 to handle system vs user queries or more)
• What trade-offs would you be happy with? For instance would it be ok if low-priority queries were rate-limited even in the absence of higher-priority queries?

Some related issues include #37856 (don't let queries that target lots of shards slow down more reasonable queries) and #14224 (priorities, but at index-time).