# MARS-956: Exporting Historical data for ODS: C2D MPEC (delta)

## Overview

**Purpose**: One-time export of historical C2D MPEC delta data from operational database (OU_C2D) to DATA bucket as CSV files.

**Approach**: Use DATA_EXPORTER export functionality EXPORT_TABLE_DATA for bulk data movement with file registration.

**Input**: Old tables in OU_C2D operational database  
**Output**: CSV files in DATA bucket  
**Mapping**: Structure must match new ODS template tables

## Tables to Export

| Source Table (OU_C2D) | Target Location (DATA) | Export Type | Time Dependency |
|------------------------|-------------------------|-------------|------------------|
| `MPEC_ADMIN` | `mrds_data_dev/DATA/C2D/C2D_MPEC_ADMIN` | CSV to DATA | Sync with REL_02 |
| `MPEC_CONTENT` | `mrds_data_dev/DATA/C2D/C2D_MPEC_CONTENT` | CSV to DATA | Sync with REL_02 |
| `MPEC_CONTENT_CRITERION` | `mrds_data_dev/DATA/C2D/C2D_MPEC_CONTENT_CRITERION` | CSV to DATA | Sync with REL_02 |

## Export Strategy

- **Format**: CSV files in DATA bucket
- **Reason**: Complete history of delta records needed for all queries
- **Method**: `DATA_EXPORTER.EXPORT_TABLE_DATA` procedure
- **Bucket Area**: `'DATA'`
- **Folder Structure**: `'DATA/C2D/{TABLE_NAME}'`
- **File Registration**: Files registered in A_SOURCE_FILE_RECEIVED table

## Installation Steps

1. Run master install script: `@install_mars956.sql`
2. Verify exports completed successfully
3. Confirm CSV files created in DATA bucket with expected structure

## Files Structure

```
MARS-956/
├── README.md                           # This file
├── install_mars956.sql                 # Master installation script
├── 01_MARS_956_export_c2d_mpec_data.sql # Export procedures execution
├── track_package_versions.sql          # Universal version tracking
├── verify_packages_version.sql         # Universal version verification
└── rollback_mars956.sql               # Rollback script (if needed)
```

## Prerequisites

- OU_C2D schema access for source tables
- DATA_EXPORTER package v2.7.5+ deployed (with pRegisterExport support)
- DEF_CRED_ARN credentials configured
- DATA bucket accessible

## Post-Installation Verification

1. Check export completion in A_PROCESS_LOG
2. Verify CSV files created in DATA bucket
3. Validate file structure matches template tables
4. Confirm row counts match source tables
5. Check file registration in A_SOURCE_FILE_RECEIVED table

## Notes

- This is a **one-time** data migration
- No package modifications required (uses existing DATA_EXPORTER)
- Export timing critical - must sync with REL_02 deployment
- Complete history required for delta queries