The mydatasyncer is a utility for synchronizing data from various file formats to a relational database. It provides flexible synchronization options including full overwrite and differential update modes.

Features

• Two sync modes:
  • Overwrite mode: Completely replaces all existing data in the target table
  • Differential mode: Updates only changed records, adds new records, and optionally deletes records not in the source file
• Multi-table synchronization: Supports synchronizing multiple tables with dependency-aware ordering
• Parent-child relationships: Automatic sync order determination based on foreign key dependencies
• Bulk operations: Efficiently handles large datasets using bulk insert/update/delete operations
• Transaction support: All operations are wrapped in database transactions to ensure data integrity
• Simple configuration: Easy to define target tables, columns, and primary keys
• Multiple format support: Supports CSV and JSON formats with automatic type detection

Installation

Prerequisites

• Go 1.16 or later
• MySQL or compatible database (configurable for other database systems)

Installing with go install

The simplest way to install mydatasyncer is to use go install:

go install github.com/yoRyuuuuu/mydatasyncer@latest

This will install the latest version of mydatasyncer in your Go bin directory, which should be in your PATH.

Building from Source

Alternatively, you can build from source:

git clone https://github.com/yoRyuuuuu/mydatasyncer.git
cd mydatasyncer
go build

Usage

Basic Usage

mydatasyncer --config config.yml

Dry Run Mode

The Dry Run mode allows you to preview synchronization changes without actually modifying the database.

Overview

Key benefits of the Dry Run feature:

• Safe Change Preview: Review synchronization results without affecting the actual database
• Detailed Execution Plan: Check the number of records to be inserted, updated, or deleted, and which columns will be affected
• Transaction Protection: Changes are automatically rolled back in Dry Run mode, ensuring data integrity
• Dual Mode Support: Available in both overwrite and diff modes

Usage

1. Command Line Execution:

# Basic usage
mydatasyncer --config config.yml --dry-run

# Without config path (uses default mydatasyncer.yml)
mydatasyncer --dry-run

2. Configuration File:

# mydatasyncer.yml
db:
  dsn: "user:password@tcp(127.0.0.1:3306)/testdb?parseTime=true"
sync:
  filePath: "./testdata.csv"
  tableName: "products"
  columns:
    - id
    - name
    - price
  primaryKey: "id"
  syncMode: "diff"
  deleteNotInFile: true

Output Format

The Dry Run mode displays an execution plan in the following format:

[DRY-RUN MODE] Execution Plan for Table {table_name}
----------------------------------------------------
Summary:
- Sync Mode: {overwrite|diff}
- Records in File: X
- Records in Database: Y

Planned Operations:
1. Delete Operations
   - Records to Delete: N
   - Affected Primary Keys: [key list]

2. Insert Operations
   - Records to Insert: M
   - Affected Columns: [column1, column2, ...]

3. Update Operations
   - Records to Update: P
   - Affected Columns: [column1, column2, ...]

Timestamps:
- Timestamp Columns to Update: [created_at, updated_at]

Important Notes

1. Transaction Control

   • All operations in Dry Run mode are automatically rolled back
   • No actual database changes are made during execution

2. Timestamp Columns

   • Timestamp columns (created_at, updated_at) are included in the execution plan
   • Actual values will be set automatically during real execution

3. Performance

   • Minimal performance overhead even with large datasets
   • Efficient execution plan generation with minimal database impact

4. Error Handling

   • Configuration and connection errors are detected before execution
   • Error messages are displayed in a clear, understandable format

Basic Usage

Run the synchronization with:

mydatasyncer

By default, it will use the built-in configuration. You can customize the behavior through a configuration file.

Configuration

The configuration file uses YAML format. There are two configuration styles: single-table and multi-table.

Single-Table Configuration

# Database connection settings
db:
  dsn: "user:password@tcp(127.0.0.1:3306)/testdb?parseTime=true"

# Synchronization settings
sync:
  # Input file path (CSV or JSON format)
  filePath: "./testdata.csv"

  # Target table name
  tableName: "products"

  # Columns to synchronize
  columns:
    - id          # Primary key
    - name        # Regular column
    - price       # Regular column
    - created_at  # Timestamp column
    - updated_at  # Timestamp column

  # Primary key specification (required)
  primaryKey: "id"

  # Synchronization mode
  # - "diff": Differential sync mode. Updates existing records, inserts new ones
  # - "overwrite": Overwrite mode. Deletes all existing data and replaces with file contents
  syncMode: "diff"

  # Delete records not in file (only effective in diff mode)
  deleteNotInFile: true

  # Timestamp column auto-update settings
  timestamps:
    createdAt: "created_at"  # Updated only when creating new records
    updatedAt: "updated_at"  # Updated every time records are modified

  # Immutable columns (excluded from synchronization)
  immutableColumns:
    - "created_at"  # Creation timestamp cannot be modified

Multi-Table Configuration

# Database connection settings
db:
  dsn: "user:password@tcp(127.0.0.1:3306)/testdb?parseTime=true"

# Multi-table synchronization settings
tables:
  - tableName: "categories"
    filePath: "./categories.json"
    primaryKey: "category_id"
    syncMode: "diff"
    dependencies: []  # No dependencies (parent table)
    
  - tableName: "products"
    filePath: "./products.csv"
    primaryKey: "product_id"
    syncMode: "diff"
    dependencies: ["categories"]  # Depends on categories table
    columns:
      - product_id
      - name
      - category_id
      - price
    timestamps:
      updatedAt: "updated_at"

Transaction Boundaries

Single-Table Synchronization:

• Each table sync runs in its own dedicated transaction
• If the sync fails, only that table's changes are rolled back

Multi-Table Synchronization:

• All tables are synchronized within a single global transaction
• All-or-nothing approach: If ANY table sync fails, the ENTIRE multi-table operation is rolled back
• Ensures ACID properties and referential integrity across related tables with foreign key relationships
• Dependency-aware processing order:
  • Delete operations: Child tables → Parent tables (avoids foreign key violations)
  • Insert/Update operations: Parent tables → Child tables (satisfies foreign key constraints)

Sync Mode Details

Differential Mode (diff)

• Matches existing records using primary key
• Updates only changed records
• Inserts new records
• Deletes records not in file if deleteNotInFile: true
• Executes within a transaction, rolls back all changes on error

Overwrite Mode (overwrite)

• Deletes all existing data in the table
• Completely replaces with file contents
• Faster but existing data is completely lost
• Ignores deleteNotInFile setting

Using Timestamp and Immutable Columns

1. Timestamp Columns

   • created_at: Updated with current timestamp only for new records
   • updated_at: Updated with current timestamp on every record modification
   • Timestamp columns must be included in the columns list

2. Immutable Columns

   • Specified in immutableColumns
   • Values once set will not be modified during synchronization
   • Typically used to protect metadata or system management fields

Usage Examples

1. Product Master Differential Sync

sync:
  filePath: "./products.csv"
  tableName: "products"
  columns:
    - product_id
    - name
    - price
    - category
    - created_at
    - updated_at
  primaryKey: "product_id"
  syncMode: "diff"
  deleteNotInFile: false  # Don't delete products
  timestamps:
    createdAt: "created_at"
    updatedAt: "updated_at"

2. User Data Complete Sync

sync:
  filePath: "./users.csv"
  tableName: "users"
  columns:
    - user_id
    - email
    - name
    - status
    - created_at
  primaryKey: "user_id"
  syncMode: "overwrite"  # Complete replacement
  immutableColumns:
    - "created_at"  # Preserve creation timestamp

3. Inventory Differential Update (with deletions)

sync:
  filePath: "./inventory.csv"
  tableName: "inventory"
  columns:
    - item_id
    - quantity
    - last_checked
    - updated_at
  primaryKey: "item_id"
  syncMode: "diff"
  deleteNotInFile: true  # Remove out-of-stock items
  timestamps:
    updatedAt: "updated_at"

Using with Docker

A Docker Compose setup is included for easy development and testing:

# Start the MySQL database
docker compose up -d

# Build and run the application
go build
./mydatasyncer

The provided compose.yml sets up a MySQL database and initializes it with sample tables.

Project Structure

• main.go: Entry point and CSV file loading logic
• dbsync.go: Database synchronization operations
• config.go: Configuration definitions and loading
• init-sql/: SQL files for database initialization
• testdata.csv: Sample data file for testing

License

This project is licensed under the MIT License - see the LICENSE file for details.

Future Enhancements

• Support for additional file formats (Excel, JSON, XML)
• Configuration through external files (YAML, TOML, JSON)
• Command-line parameters for overriding configuration
• Enhanced logging and monitoring features
• Support for additional database systems