CHANGE: Added refactoring notes

partitioning/REFACTORING_NOTES.md

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+# Refactoring Notes: Zabbix Partitioning Script
+
+## Overview
+The `zabbix_partitioning.py` script has been significantly refactored to improve maintainability, reliability, and compatibility with modern Zabbix versions (7.x).
+
+## Key Changes
+
+### 1. Architecture: Class-Based Structure
+- **Old**: Procedural script with global variables and scattered logic.
+- **New**: Encapsulated in a `ZabbixPartitioner` class.
+- **Purpose**: Improves modularity, testability, and state management. Allows the script to be easily imported or extended.
+
+### 2. Database Connection Management
+- **Change**: Implemented `contextlib.contextmanager` for database connections.
+- **Purpose**: Ensures database connections are robustly opened and closed, even if errors occur. Handles `wait_timeout` and binary logging settings automatically for every session.
+
+### 3. Logging
+- **Change**: Replaced custom `print` statements with Python's standard `logging` module.
+- **Purpose**: 
+  - Allows consistent log formatting.
+  - Supports configurable output destinations (Console vs Syslog) via the config file.
+  - Granular log levels (INFO for standard ops, DEBUG for SQL queries).
+
+### 4. Configuration Handling
+- **Change**: Improved validation and parsing of the YAML configuration.
+- **Purpose**: 
+  - Removed unused parameters (e.g., `timezone`, as the script relies on system local time).
+  - Added support for custom database ports (critical for non-standard deployments or containerized tests).
+  - Explicitly handles the `replicate_sql` flag to control binary logging (it was intergrated into the partitioning logic).
+
+### 5. Type Safety
+- **Change**: Added comprehensive Python type hinting (e.g., `List`, `Dict`, `Optional`).
+- **Purpose**: Makes the code self-documenting and allows IDEs/linters to catch potential errors before execution.
+
+### 6. Zabbix 7.x Compatibility
+- **Change**: Added logic to verify Zabbix database version and schema requirements.
+- **Purpose**: 
+  - Checks `dbversion` table.
+  - **Critical**: Validates that target tables have the `clock` column as part of their Primary Key before attempting partitioning, preventing potential data corruption or MySQL errors.