[GitHub] [shardingsphere] RaigorJiang opened a new issue, #24779: Difficult to drop readwrite_splitting rule with DistSQL

["RaigorJiang (via GitHub)" <gi...@apache.org>]

RaigorJiang opened a new issue, #24779:
URL: https://github.com/apache/shardingsphere/issues/24779

   ## Enhancement request
   
   ### Which version of ShardingSphere did you use?
   master 858305dc
   
   ### Which project did you use? ShardingSphere-JDBC or ShardingSphere-Proxy?
   ShardingSphere-Proxy
   
   ### Actual behavior
   After creating a readwrite_splitting rule, if there are some single tables in the database, the rule cannot be dropped.
   
   ### Impact
   I discussed this limitation in a previous issue #22058. Limiting drop is to ensure business security, but it does bring inconvenience to actual use.
   
   Consider such a scenario:
   1. The user registers two storage units and configures the readwrite_splitting rule with them.
   2. When one of the storage units fails and the address needs to be changed:
   - Cannot ALTER storage unit, not allowed
   - Cannot DROP the storage unit because it is used by the readwrite_splitting rule
   3. Next, the user tries to DROP the readwrite_splitting rule, maybe the readwrite_splitting rule is also being used (if no sharding rule depends on it, there may be many single tables)
   
   At this point, the user may not know what to do.
   
   ### Suggestion
   For these special but tricky situations, I suggest referring to `UNREGISTER STORAGE UNIT`, adding the `IGNORE SINGLE TABLES` option to `DROP READWRITE_SPLITTING RULE`, so that if only single tables depend on the readwrite_splitting rule, the user can forcefully drop the rule and recreate a new one.
   
   Of course, this process requires the user to stop executing business SQL to ensure correctness.
   


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