|
| 1 | +# async-cassandra-bulk Progress Summary |
| 2 | + |
| 3 | +## Current Status |
| 4 | +- **Date**: 2025-07-11 |
| 5 | +- **Branch**: bulk |
| 6 | +- **State**: Production-ready, awaiting release decision |
| 7 | + |
| 8 | +## What We've Built |
| 9 | +A production-ready bulk operations library for Apache Cassandra with comprehensive writetime/TTL filtering and export capabilities. |
| 10 | + |
| 11 | +## Key Features Implemented |
| 12 | + |
| 13 | +### 1. Writetime/TTL Filtering |
| 14 | +- Filter data by writetime (before/after specific timestamps) |
| 15 | +- Filter by TTL values |
| 16 | +- Support for multiple columns with "any" or "all" matching |
| 17 | +- Automatic column detection from table metadata |
| 18 | +- Precision preservation (microseconds) |
| 19 | + |
| 20 | +### 2. Export Formats |
| 21 | +- **JSON**: With precise timestamp serialization |
| 22 | +- **CSV**: With proper escaping and writetime columns |
| 23 | +- **Parquet**: With PyArrow integration |
| 24 | + |
| 25 | +### 3. Advanced Capabilities |
| 26 | +- Token-based parallel export for distributed reads |
| 27 | +- Checkpoint/resume for fault tolerance |
| 28 | +- Progress tracking with callbacks |
| 29 | +- Memory-efficient streaming |
| 30 | +- Configurable batch sizes and concurrency |
| 31 | + |
| 32 | +## Testing Coverage |
| 33 | + |
| 34 | +### 1. Integration Tests (100% passing - 106 tests) |
| 35 | +- All Cassandra data types with writetime |
| 36 | +- NULL handling (explicit NULL vs missing columns) |
| 37 | +- Empty collections behavior (stored as NULL in Cassandra) |
| 38 | +- UDTs, tuples, nested collections |
| 39 | +- Static columns |
| 40 | +- Clustering columns |
| 41 | + |
| 42 | +### 2. Error Scenarios (comprehensive) |
| 43 | +- Network failures (intermittent and total) |
| 44 | +- Disk space exhaustion |
| 45 | +- Corrupted checkpoints |
| 46 | +- Concurrent exports |
| 47 | +- Thread pool exhaustion |
| 48 | +- Schema changes during export |
| 49 | +- Memory pressure with large rows |
| 50 | + |
| 51 | +### 3. Critical Fixes Made |
| 52 | +- **Timestamp parsing**: Fixed microsecond precision handling |
| 53 | +- **NULL writetime**: Corrected filter logic for NULL values |
| 54 | +- **Precision preservation**: ISO format for CSV/JSON serialization |
| 55 | +- **Error handling**: Capture in stats rather than raising exceptions |
| 56 | + |
| 57 | +## Code Quality |
| 58 | +- ✅ All linting passed (ruff, black, isort, mypy) |
| 59 | +- ✅ Comprehensive docstrings with production context |
| 60 | +- ✅ No mocking in integration tests |
| 61 | +- ✅ Thread-safe implementation |
| 62 | +- ✅ Proper resource cleanup |
| 63 | + |
| 64 | +## Architecture Decisions |
| 65 | +1. **Thin wrapper** around cassandra-driver |
| 66 | +2. **Reuses async-cassandra** for all DB operations |
| 67 | +3. **Stateless operation** with checkpoint support |
| 68 | +4. **Producer-consumer pattern** for parallel export |
| 69 | +5. **Pluggable exporter interface** for format extensibility |
| 70 | + |
| 71 | +## Files Changed/Created |
| 72 | + |
| 73 | +### New Library Structure |
| 74 | +``` |
| 75 | +libs/async-cassandra-bulk/ |
| 76 | +├── src/async_cassandra_bulk/ |
| 77 | +│ ├── __init__.py |
| 78 | +│ ├── operators/ |
| 79 | +│ │ ├── __init__.py |
| 80 | +│ │ └── bulk_operator.py |
| 81 | +│ ├── exporters/ |
| 82 | +│ │ ├── __init__.py |
| 83 | +│ │ ├── base.py |
| 84 | +│ │ ├── csv.py |
| 85 | +│ │ ├── json.py |
| 86 | +│ │ └── parquet.py |
| 87 | +│ ├── serializers/ |
| 88 | +│ │ ├── __init__.py |
| 89 | +│ │ ├── base.py |
| 90 | +│ │ ├── ttl.py |
| 91 | +│ │ └── writetime.py |
| 92 | +│ ├── models.py |
| 93 | +│ ├── parallel_export.py |
| 94 | +│ └── exceptions.py |
| 95 | +├── tests/ |
| 96 | +│ ├── integration/ |
| 97 | +│ │ ├── test_bulk_export_basic.py |
| 98 | +│ │ ├── test_checkpoint_resume.py |
| 99 | +│ │ ├── test_error_scenarios_comprehensive.py |
| 100 | +│ │ ├── test_null_handling_comprehensive.py |
| 101 | +│ │ ├── test_parallel_export.py |
| 102 | +│ │ ├── test_serializers.py |
| 103 | +│ │ ├── test_ttl_export.py |
| 104 | +│ │ ├── test_writetime_all_types_comprehensive.py |
| 105 | +│ │ ├── test_writetime_export.py |
| 106 | +│ │ └── test_writetime_filtering.py |
| 107 | +│ └── unit/ |
| 108 | +│ ├── test_exporters.py |
| 109 | +│ └── test_models.py |
| 110 | +├── pyproject.toml |
| 111 | +├── README.md |
| 112 | +└── examples/ |
| 113 | + └── bulk_export_example.py |
| 114 | +``` |
| 115 | + |
| 116 | +### Removed from async-cassandra |
| 117 | +- `examples/bulk_operations/` directory |
| 118 | +- `examples/export_large_table.py` |
| 119 | +- `examples/export_to_parquet.py` |
| 120 | +- `examples/exampleoutput/` directory |
| 121 | +- Updated `Makefile` to remove bulk-related targets |
| 122 | +- Updated `examples/README.md` |
| 123 | +- Updated `examples/requirements.txt` |
| 124 | +- Updated `tests/integration/test_example_scripts.py` |
| 125 | + |
| 126 | +## Open Questions for Research |
| 127 | + |
| 128 | +### Current Implementation |
| 129 | +- Uses token ranges for distribution |
| 130 | +- Leverages prepared statements |
| 131 | +- Implements streaming to avoid memory issues |
| 132 | +- Supports writetime/TTL filtering at query level |
| 133 | + |
| 134 | +### Potential Research Areas |
| 135 | +1. **Different partitioning strategies?** |
| 136 | + - Current: Token-based ranges |
| 137 | + - Alternative: Partition key based? |
| 138 | + |
| 139 | +2. **Alternative export mechanisms?** |
| 140 | + - Current: Producer-consumer with queues |
| 141 | + - Alternative: Direct streaming? |
| 142 | + |
| 143 | +3. **Integration with other bulk tools?** |
| 144 | + - Spark Cassandra Connector patterns? |
| 145 | + - DataStax Bulk Loader compatibility? |
| 146 | + |
| 147 | +4. **Performance optimizations?** |
| 148 | + - Larger page sizes? |
| 149 | + - Different threading models? |
| 150 | + - Connection pooling strategies? |
| 151 | + |
| 152 | +## Next Steps |
| 153 | +1. Decide on research direction for bulk operations |
| 154 | +2. Tag and release if current approach is acceptable |
| 155 | +3. Or refactor based on research findings |
| 156 | + |
| 157 | +## Key Takeaways |
| 158 | +- The library is **production-ready** as implemented |
| 159 | +- Comprehensive test coverage ensures reliability |
| 160 | +- Architecture allows for future enhancements |
| 161 | +- Clean separation from main async-cassandra library |
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