terrymanu commented on issue #37014:
URL:
https://github.com/apache/shardingsphere/issues/37014#issuecomment-3494688215
ShardingSphere does provide complete storage unit management functionality,
and you can safely delete unavailable storage units through DistSQL.
Root Cause Analysis
ShardingSphere attempts to connect to all registered storage units during
startup to detect database types. This occurs in the
DatabaseTypeEngine.getStorageType() method. If the database corresponding to a
storage unit is
inaccessible, it will cause startup failure.
Solution: Use UNREGISTER STORAGE UNIT
ShardingSphere provides complete DistSQL syntax for managing storage units:
Basic Syntax
-- Delete a single storage unit
UNREGISTER STORAGE UNIT storage_unit_name;
-- Delete multiple storage units
UNREGISTER STORAGE UNIT ds_0, ds_1;
-- Safe deletion (delete if exists, no error if not exists)
UNREGISTER STORAGE UNIT IF EXISTS storage_unit_name;
Force Deletion Options
If storage units are being used by rules, you can use the following
options:
-- Force deletion (ignore single table rules)
UNREGISTER STORAGE UNIT storage_unit_name IGNORE SINGLE TABLES;
-- Force deletion (ignore broadcast table rules)
UNREGISTER STORAGE UNIT storage_unit_name IGNORE BROADCAST TABLES;
-- Force deletion (ignore single table and broadcast table rules)
UNREGISTER STORAGE UNIT storage_unit_name IGNORE SINGLE, BROADCAST TABLES;
Specific Operation Steps
1. Start ShardingSphere-Proxy: Even with connection errors, Proxy usually
starts and accepts management connections
2. Connect to Proxy: Use a MySQL client to connect to Proxy's management
port
3. Execute DistSQL commands:
-- View current storage units
SHOW STORAGE UNITS;
-- Delete unavailable storage unit
UNREGISTER STORAGE UNIT IF EXISTS problem_storage_name;
4. Restart ShardingSphere-Proxy: After deleting the unavailable storage
unit, restart should proceed normally
Conclusion
The issue you encountered is not a technical limitation but rather
information asymmetry. ShardingSphere already provides complete storage unit
lifecycle management functionality. You can safely delete unavailable storage
unit configurations using the UNREGISTER STORAGE UNIT DistSQL command.
When encountering such issues, it is recommended to first clean up unavailable
configurations using this command, then restart the service.
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