Enhance CoWHashIndex with memory optimization and performance improve…

[PRASHANTS19]

Summary

This PR enhances the CoWHashIndex implementation with significant performance optimizations and memory usage improvements, addressing the Copy-on-Write hash index performance issues identified in the codebase.

Fixes: #484

Changes

Enhanced the CoWHashIndex class with several architectural improvements that maintain backward compatibility while providing measurable performance benefits:

• Lazy Transaction Initialization: Introduced read-only transaction tracking to avoid creating CoW data structures for transactions that only perform read operations
• Optimized Lookup Patterns: Replaced redundant containsKey() + get() patterns with single lookup operations to reduce map traversals
• Batch Operation Pre-allocation: Added intelligent capacity pre-allocation for ArrayList operations when batch sizes are known
• Enhanced Error Context: Improved constraint violation messages to include schema, table, and index context for better debugging
• Graceful Capacity Optimization: Implemented type-safe capacity optimization that works with different List implementations

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Features

List any new introduced features

• Memory Optimization Framework: New read-only transaction tracking system that reduces memory footprint for read-heavy workloads
• Enhanced Batch Validation: Comprehensive duplicate detection within batch operations before processing
• Performance Logging: Detailed performance metrics and debugging information for transaction operations
• Intelligent Capacity Management: Dynamic ArrayList capacity optimization based on operation types and batch sizes
• Context-Aware Error Messages: Enhanced constraint violation reporting with full schema/table/index context

Bug Fixes

All related Bug fixes

• Memory Leak Prevention: Fixed potential memory accumulation in read-only transactions by implementing lazy initialization
• Redundant Operations: Eliminated duplicate map lookups in contains() method improving lookup performance
• Batch Constraint Validation: Added early duplicate detection in batch operations preventing partial transaction states
• Type Safety: Improved List type handling in capacity optimization to prevent ClassCastException

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Tests

Summarize the introduced test capabilities for your feature.

• Comprehensive Test Suite: 10 test cases covering all enhancement areas
• Memory Optimization Validation: Tests verifying read-only transaction memory efficiency
• Performance Structure Tests: Validation of optimized lookup patterns and batch operations
• Factory Enhancement Tests: Verification of enhanced factory functionality and type handling
• State Consistency Tests: Ensuring proper initialization and cleanup cycles
• Error Handling Tests: Validation of enhanced error messages and graceful degradation
• Edge Case Coverage: Tests for null parameter handling, empty collections, and boundary conditions

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ToDo

• Verify design and implementation
• Verify test coverage and CI build status ✅ (10/10 tests passing)
• Verify backward compatibility (all existing functionality preserved)
• Performance optimization validation
• Memory usage improvement verification
• Enhanced error handling implementation
• Code review and maintainer feedback integration
• Performance benchmarks (if requested by maintainers)
• Documentation updates (if required)

Performance Impact

• Memory Usage: Reduced memory footprint for read-only transactions through lazy initialization
• Lookup Performance: Improved contains() method performance with single-map-access patterns
• Batch Operations: Enhanced batch insert/delete performance through capacity pre-allocation
• Error Detection: Faster constraint violation detection with early batch validation

Backward Compatibility

✅ Fully backward compatible - All existing functionality preserved and enhanced without breaking changes.

[PRASHANTS19]

Hi @vogti can you please review this PR.