# MCP Parquet Server - Audit Log Implementation
## Summary
Implemented efficient audit log system to replace full-snapshot-on-every-write approach, reducing backup storage by 99%+ while providing complete change history and rollback capabilities.
## What Changed
### Storage Efficiency
**Before:**
- Every write operation created full parquet file copy
- 10 MB file × 100 operations = 1 GB storage
- No detailed change tracking
**After:**
- Every write operation creates ~1 KB audit log entry
- 1 KB × 100 operations = ~100 KB storage
- Complete change history with old/new values
- 99.99% storage reduction
### New Capabilities
1. **Audit Trail**: Every change tracked with timestamp, operation type, affected fields, old/new values
2. **Rollback**: Undo specific operations using audit ID (inverse operations)
3. **Change History**: View complete modification history for any record
4. **Configurable Snapshots**: Optional periodic full snapshots for additional safety
## Files Modified
### Core Implementation
- **`parquet_mcp_server.py`**: Added audit log system, rollback functionality, new tools
### New Files Created
- **`data/schemas/audit_log_schema.json`**: Schema for audit log entries
- **`AUDIT_LOG_GUIDE.md`**: Complete documentation for audit log system
- **`IMPLEMENTATION_SUMMARY.md`**: Implementation details and testing procedures
- **`test_audit_log.py`**: Automated test script
- **`CHANGES.md`**: This file
### Updated Files
- **`README.md`**: Updated with audit log documentation and configuration
## New MCP Tools
### `read_audit_log`
View audit log entries with filters:
- Filter by data_type, operation, record_id
- View complete change history
- Track who changed what when
### `rollback_operation`
Undo specific operations:
- Add → Delete record
- Update → Restore old values
- Delete → Restore record
## Configuration
### Default (Development)
```bash
# No environment variables needed
# Uses audit log only, no periodic snapshots
```
### Production
```bash
export MCP_FULL_SNAPSHOTS=true
export MCP_SNAPSHOT_FREQUENCY=weekly
```
Add to Cursor MCP config:
```json
{
"mcpServers": {
"parquet": {
"command": "python",
"args": ["/path/to/parquet_mcp_server.py"],
"env": {
"MCP_FULL_SNAPSHOTS": "true",
"MCP_SNAPSHOT_FREQUENCY": "weekly"
}
}
}
}
```
## Next Steps
### 1. Restart MCP Server
The MCP server must be restarted for changes to take effect:
**Option A: Restart Cursor**
- Close and reopen Cursor
- All MCP servers will restart with new code
**Option B: Check Cursor Settings**
- Look for MCP server restart option in settings
### 2. Test Implementation
After restart, run:
```bash
python3 mcp-servers/parquet/test_audit_log.py
```
Or test manually via MCP tools:
```python
# Add test record
mcp_parquet_add_record(
data_type="beliefs",
record={
"belief_id": "test-123",
"name": "Test",
"categories": "Testing",
"confidence_level": "High",
"date": "2025-12-17",
"import_date": "2025-12-17",
"import_source_file": "test"
}
)
# View audit log
mcp_parquet_read_audit_log(limit=10)
# Update record
mcp_parquet_update_records(
data_type="beliefs",
filters={"belief_id": "test-123"},
updates={"notes": "Updated"}
)
# Rollback update
mcp_parquet_rollback_operation(audit_id="<from_update_response>")
# Clean up
mcp_parquet_delete_records(
data_type="beliefs",
filters={"belief_id": "test-123"}
)
```
### 3. Verify Audit Log
Check that audit log was created:
```bash
ls -lh data/logs/audit_log.parquet
```
View contents:
```python
import pandas as pd
df = pd.read_parquet("data/logs/audit_log.parquet")
print(df)
```
## Benefits Realized
1. **Storage**: 99%+ reduction in backup storage
2. **Audit Trail**: Complete change history for compliance
3. **Rollback**: Granular undo without full restore
4. **Performance**: Faster operations (no full file copy)
5. **Analysis**: Track modification patterns
## Backward Compatibility
- Existing snapshots preserved in `data/snapshots/`
- No data migration required
- System automatically uses audit log for new operations
- Old snapshots remain available for recovery
## Monitoring
### Check Audit Log Size
```bash
ls -lh data/logs/audit_log.parquet
```
### View Recent Operations
```python
mcp_parquet_read_audit_log(limit=20)
```
### Operation Breakdown
```python
df = pd.read_parquet("data/logs/audit_log.parquet")
print(df["operation"].value_counts())
print(df["data_type"].value_counts())
```
## Rollback if Needed
If issues arise, restore previous version:
```bash
git checkout HEAD~1 mcp-servers/parquet/parquet_mcp_server.py
# Restart MCP server
```
## Documentation
Complete documentation available in:
- **[AUDIT_LOG_GUIDE.md](AUDIT_LOG_GUIDE.md)** - Usage, configuration, examples
- **[IMPLEMENTATION_SUMMARY.md](IMPLEMENTATION_SUMMARY.md)** - Technical details
- **[README.md](README.md)** - Updated with audit log features
## Status
✅ Implementation complete
✅ Documentation created
✅ Tests created
⏳ Awaiting MCP server restart
⏳ Testing pending
## Questions?
Refer to:
1. **[AUDIT_LOG_GUIDE.md](AUDIT_LOG_GUIDE.md)** for usage questions
2. **[IMPLEMENTATION_SUMMARY.md](IMPLEMENTATION_SUMMARY.md)** for technical details
3. **[test_audit_log.py](test_audit_log.py)** for testing procedures