terrymanu commented on issue #24395:
URL:
https://github.com/apache/shardingsphere/issues/24395#issuecomment-3539947496
## Problem Understanding
You're experiencing issues with ShardingSphere-Proxy when executing these
queries:
1. SELECT * FROM information_schema.tables; - Returns empty results +
NullPointerException
2. SELECT * FROM information_schema.columns; - IndexOutOfBoundsException:
"Index 20 out of bounds for length 20"
## Root Cause Analysis
After code analysis, the core reasons for this issue are:
🔍 Current Implementation Status
- ✅ information_schema.SCHEMATA table is fully implemented (related bugs
fixed in August 2024)
- ❌ TABLES and COLUMNS tables lack dedicated implementation, relying on
generic DatabaseMetaDataExecutor
🎯 Root Causes
1. Experimental Feature Limitation: information_schema in ShardingSphere
is still marked as experimental
2. Incomplete Implementation: Only SCHEMATA has dedicated handlers, other
tables use generic processing logic
3. Insufficient Edge Case Handling: DatabaseMetaDataExecutor doesn't
handle all edge cases properly in certain metadata scenarios
📊 Current Status
- Issue remains in "status: volunteer wanted" state
- Master branch doesn't yet include complete fixes for TABLES/COLUMNS
- Community contribution needed for full implementation
## Solutions
🚀 Workaround Solutions (Recommended)
1. Bypass ShardingSphere: Use direct database connection for Laravel
migrate operations
2. Version Upgrade: Use latest ShardingSphere version (though issues may
persist)
3. Configuration Adjustment: Configure Laravel to skip information_schema
related queries
🔧 Long-term Solution
Requires community contribution to implement:
- Dedicated SelectInformationTablesExecutor and
SelectInformationColumnsExecutor
- Improved exception handling and boundary checks
- Complete unit test coverage
## Recommendation: Given this is an experimental feature, it's advisable to
avoid information_schema related queries in production environments or connect
directly to the native database for schema-related operations.
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