Is your feature request related to a problem? Please describe
We discussed and removed the restriction on the scale down operation in #20938: the number of search only replicas must be greater than 0.
This is very helpful in scenarios where a storage-compute separation architecture is already in use but a read-write separation architecture is not.
However, this introduces a new problem. If the query fails because the number of search only replicas is 0, we can only see the vague "all shards failed" exception.
Describe the solution you'd like
I plan to provide clear exception messages for the following two scenarios.
- The query used preference
"_search_replica" && the number of search only shards is 0
- The query did not use preference
"_search_replica" && the number of search only shards is 0 && INDEX_BLOCKS_SEARCH_ONLY_SETTING is true
Related component
Search
Describe alternatives you've considered
No response
Additional context
No response
Is your feature request related to a problem? Please describe
We discussed and removed the restriction on the scale down operation in #20938: the number of search only replicas must be greater than
0.This is very helpful in scenarios where a storage-compute separation architecture is already in use but a read-write separation architecture is not.
However, this introduces a new problem. If the query fails because the number of search only replicas is
0, we can only see the vague"all shards failed"exception.Describe the solution you'd like
I plan to provide clear exception messages for the following two scenarios.
"_search_replica"&& the number of search only shards is0"_search_replica"&& the number of search only shards is0&&INDEX_BLOCKS_SEARCH_ONLY_SETTINGistrueRelated component
Search
Describe alternatives you've considered
No response
Additional context
No response