# MARS-1096: Extend A_PROCESS_LOG and Enable Daily Interval Partitioning

## Scope
- Extend `CT_MRDS.A_PROCESS_LOG.LOG_MESSAGE` to `VARCHAR2(20000)`
- Convert table to interval partitioning by day on `LOG_TIMESTAMP`
- **CRITICAL**: Preserves all existing data during conversion

## Strategy
- Creates new partitioned table `A_PROCESS_LOG_NEW`
- Copies ALL existing records (preserving data integrity)
- Renames old table to `A_PROCESS_LOG_OLD` (backup)
- Renames new table to `A_PROCESS_LOG`
- Manual cleanup of backup table after verification

## Files
- Baseline update: `mrds_elt-dev-database/database/CT_MRDS/SCHEMA/tables/A_PROCESS_LOG.sql`
- Migration: `MARS_Packages/migrations/004_extend_log_message_and_partition.sql`
- Rollback: `MARS_Packages/migrations/rollback/004_rollback_log_message_and_partition.sql`
- Install: `MARS_Packages/REL02/MARS-1096/install_mars1096.sql` (includes cleanup)
- Verify: `MARS_Packages/REL02/MARS-1096/04_MARS_1096_verify_partitioning.sql`
- Cleanup: `MARS_Packages/REL02/MARS-1096/05_MARS_1096_cleanup_backup.sql` (auto-executed)

## Install
```powershell
# Run with SQLcl - includes verification and automatic backup cleanup
sql "CT_MRDS/Cloudpass#34@ggmichalski_high" "@MARS_Packages/REL01/MARS-1096/install_mars1096.sql"
```

## Rollback
```powershell
# Execute rollback with full logging and verification
sql "CT_MRDS/Cloudpass#34@ggmichalski_high" "@MARS_Packages/REL01/MARS-1096/rollback_mars1096.sql"

# Log file created: ROLLBACK_MARS_1096_<PDB>_<timestamp>.log
```

**Rollback Process:**
1. User confirmation required (type "YES")
2. Restore table to non-partitioned structure
3. Revert log_message to VARCHAR2(4000)
4. Preserve all existing data
5. Verify changes with automatic checks

## Performance Notes
- Daily partitions optimal for ~200k records/day
- Partition pruning improves query performance with date filters
- Local indexes can be added per partition if needed
