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ORACLEDB_MIGRATION.md

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+# Migration to oracledb (from cx_Oracle)
+
+## Overview
+
+The project has been updated to use **oracledb** instead of **cx_Oracle**:
+
+### Benefits of oracledb
+
+| Feature | cx_Oracle | oracledb |
+|---------|-----------|----------|
+| **Oracle Instant Client Required** | ✓ Always | ✗ Not in Thin mode |
+| **Setup Complexity** | Complex | Simple |
+| **Thin Mode** | ✗ No | ✓ Yes (default) |
+| **Modern** | Older | Latest |
+| **Python 3.8+** | ✓ | ✓ |
+| **Connection Pooling** | ✓ | ✓ |
+
+### What Changed
+
+#### Dependencies
+
+**Before:**
+```txt
+cx_Oracle==8.3.0
+```
+
+**After:**
+```txt
+oracledb==2.0.0
+```
+
+#### Code Changes
+
+**oracle_connector.py:**
+- Changed `import cx_Oracle` → `import oracledb`
+- Changed `cx_Oracle.SessionPool` → `oracledb.create_pool()`
+- Added Thin mode initialization (no Instant Client needed)
+- Updated exception handling to `oracledb.DatabaseError`
+
+#### Installation
+
+**Before (cx_Oracle):**
+- 1. Install Python package
+- 2. Download Oracle Instant Client
+- 3. Install Oracle Instant Client
+- 4. Set LD_LIBRARY_PATH
+- 5. Test connection
+
+**After (oracledb Thin mode):**
+- 1. Install Python package → Done! ✓
+
+No Oracle Instant Client needed for Thin mode!
+
+---
+
+## Quick Setup
+
+### Option 1: Thin Mode (Recommended - No Installation)
+
+```bash
+# Install dependencies
+pip install -r requirements.txt
+
+# That's it! oracledb Thin mode works without Oracle Instant Client
+python -c "import oracledb; print('Ready to use!')"
+```
+
+**Works for:**
+- ✓ Network connections to remote Oracle Database
+- ✓ All standard SQL operations
+- ✓ Connection pooling
+- ✓ Most applications
+
+### Option 2: Thick Mode (If You Have Oracle Instant Client)
+
+If you already have Oracle Instant Client installed, you can optionally use Thick mode:
+
+```bash
+# Edit db/oracle_connector.py and uncomment:
+# oracledb.init_oracle_client()  # Use Thick mode
+```
+
+---
+
+## Testing the Connection
+
+### Test Database Connectivity
+
+```bash
+python -c "
+import oracledb
+
+# Using Thin mode (default)
+try:
+    connection = oracledb.connect(
+        user='pacs_db',
+        password='pacs_db',
+        dsn='testipksdb.c7q7defafeea.ap-south-1.rds.amazonaws.com:1521/IPKSDB'
+    )
+    print('✓ Connected successfully!')
+    connection.close()
+except Exception as e:
+    print(f'Connection error: {e}')
+"
+```
+
+---
+
+## Configuration
+
+### .env File (No Changes Needed)
+
+The configuration remains the same:
+
+```
+DB_USER=pacs_db
+DB_PASSWORD=pacs_db
+DB_HOST=testipksdb.c7q7defafeea.ap-south-1.rds.amazonaws.com
+DB_PORT=1521
+DB_SERVICE_NAME=IPKSDB
+```
+
+---
+
+## Feature Comparison
+
+### Connection Pooling
+
+Both cx_Oracle and oracledb support connection pooling:
+
+**cx_Oracle:**
+```python
+pool = cx_Oracle.SessionPool(user='...', password='...', dsn='...')
+conn = pool.acquire()
+```
+
+**oracledb:**
+```python
+pool = oracledb.create_pool(user='...', password='...', dsn='...')
+conn = pool.acquire()
+```
+
+### Query Execution
+
+No changes needed - the API is compatible:
+
+```python
+cursor = conn.cursor()
+cursor.execute("SELECT * FROM table")
+rows = cursor.fetchall()
+```
+
+---
+
+## Troubleshooting
+
+### ImportError: No module named 'oracledb'
+
+Install the package:
+```bash
+pip install oracledb==2.0.0
+```
+
+Or install all requirements:
+```bash
+pip install -r requirements.txt
+```
+
+### Connection Failed
+
+1. Verify credentials in .env:
+```bash
+cat .env | grep DB_
+```
+
+2. Test connection directly:
+```bash
+python -c "
+import oracledb
+conn = oracledb.connect(
+    user='pacs_db',
+    password='pacs_db',
+    dsn='testipksdb.c7q7defafeea.ap-south-1.rds.amazonaws.com:1521/IPKSDB'
+)
+print('Connected!')
+"
+```
+
+3. Check network connectivity:
+```bash
+# Test if database is reachable
+python -c "
+import socket
+try:
+    socket.create_connection(('testipksdb.c7q7defafeea.ap-south-1.rds.amazonaws.com', 1521), timeout=5)
+    print('✓ Database server is reachable')
+except Exception as e:
+    print(f'✗ Cannot reach database: {e}')
+"
+```
+
+---
+
+## Migration Checklist
+
+- [x] Update requirements.txt (cx_Oracle → oracledb)
+- [x] Update oracle_connector.py (imports and API)
+- [x] Update exception handling (cx_Oracle → oracledb)
+- [x] Test database connection
+- [x] Verify all tests pass
+- [x] Update documentation
+
+---
+
+## Rollback (If Needed)
+
+If you need to revert to cx_Oracle:
+
+1. Update requirements.txt:
+```txt
+cx_Oracle==8.3.0
+```
+
+2. Update oracle_connector.py:
+```python
+import cx_Oracle
+pool = cx_Oracle.SessionPool(...)
+```
+
+3. Install and test:
+```bash
+pip install -r requirements.txt
+python main.py
+```
+
+---
+
+## Performance Impact
+
+**No performance difference** - oracledb Thin mode:
+- ✓ Same connection pooling
+- ✓ Same query execution speed
+- ✓ Same transaction handling
+
+The only difference is simplified setup!
+
+---
+
+## Documentation Updates
+
+The following documentation has been updated:
+
+- ✅ SETUP.md - Simplified Oracle client section
+- ✅ requirements.txt - Updated to oracledb
+- ✅ db/oracle_connector.py - Updated to use oracledb
+- ✅ This file - Migration guide
+
+---
+
+## References
+
+- **oracledb Documentation**: https://python-oracledb.readthedocs.io/
+- **Thin vs Thick Mode**: https://python-oracledb.readthedocs.io/en/latest/user_guide/initialization.html
+- **Connection Pooling**: https://python-oracledb.readthedocs.io/en/latest/user_guide/connection_handling.html
+
+---
+
+## Summary
+
+✅ **Migration to oracledb completed successfully**
+
+**Benefits:**
+- No Oracle Instant Client needed (Thin mode)
+- Simpler installation (just `pip install`)
+- Modern Python Oracle driver
+- Same API compatibility
+- Better documentation and support
+
+**Migration Status:** Ready for production
+
+**Testing:** All tests passing with oracledb