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MARS_Packages/REL01/MARS-1096/README.md

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+# 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