JsonDB is a high-performance JSON database system that combines Redis-like key-value operations with MongoDB-like document query capabilities.
It integrates a multi-layer memory caching system to deliver optimal read and write performance.
Initially developed in Go for architecture validation, a Rust version will be provided later.

This is an extension project of go-redis-fallback, focusing on a JSON-centric database.
It explores database construction using standard libraries and serves as a foundation for learning Rust syntax.

• Architecture: Multi-layer memory cache + disk persistence
• Style: Redis-like key-value operations + MongoDB-like document queries
• Caching: LRU / memory cache structure + cache warming mechanism
• Storage: AOF logs for data safety + three-layer directory structure for JSON file storage
• TTL: Lazy deletion + automatic expiration cleanup + cache eviction policies

go/
├── cmd/
│   ├── cli/main.go          # CLI client entry point
│   └── server/main.go       # Server entry point
├── internal/
│   ├── command/             # Command parsing and types
│   │   ├── parser.go        # Command parser
│   │   └── types.go         # Command type definitions
│   ├── server/              # Server core
│   │   ├── server.go        # Server main logic
│   │   ├── client.go        # Client handling
│   │   ├── clientKV.go      # KV operations implementation
│   │   ├── clientDoc.go     # Document operations implementation
│   │   └── clientTTL.go     # TTL operations implementation
│   ├── storage/             # Storage layer
│   │   ├── config.go        # Configuration and path management
│   │   ├── aofReader.go     # AOF reader
│   │   └── aofWriter.go     # AOF writer
│   └── util/
│       └── util.go          # Utility functions
└── data/                    # Data storage directory
  ├── aof/                   # AOF log files
  │   ├── db_0.aof
  │   └── db_1.aof
  └── 0/                     # Database 0 JSON files
    └── 09/8f/6b/            # Three-layer directory structure
      └── hash.json

• Multi-database support (0-15)
• Three-layer directory structure for file storage (MD5 hash-based)
• AOF persistence mechanism (append-only log files)
• Automatic expiration cleanup (runs every minute)
• CLI client interface
• Support single-action commands using -c "SET <key>"
• Implement LRU caching mechanism
• Cache warming functionality
• Connection pool management

• SELECT <db:int> - Select database (0-15)
• GET <key> - Retrieve the value of a specified key
• SET <key> <value> [ttl_second|expire_time] - Set a key-value pair with optional expiration
• DEL <key1> [key2] ... - Delete one or more keys
• EXISTS <key> - Check if a key exists
• KEYS <pattern> - Search for keys matching a pattern
• TYPE <key> - Get the data type of a key

• FIND <key> <filters> [page:int] [offset:int] - Query documents matching conditions {filters:[]}, supports pagination
• ADD <key> <value> - Add a document to a collection
• SORT <key> <filters> <sort_by> [page:int] [offset:int] - Sort query results using {sort:[]}
• UPDATE <key> <filters> <set> - Update documents matching conditions using {set:{}}
• REMOVE <key> <filters> - Delete documents matching conditions

• TTL <key> [filters] - View the remaining time for a key
• EXPIRE <key> <ttl_second|expire_time> [filters] - Set the expiration time for a key
• PERSIST <key> [filters] - Remove the expiration setting for a key

• PING - Test connection
• HELP - Display help information
• Performance testing
• Error handling
• Unit testing

# Basic query
FIND users {"name":"John"}

# Compound query
FIND products {"category":"electronics","price":{"$lt": 1000}}

# Regex query
FIND users {"email":{"$regex":".*@gmail.com"}}

# Range query
FIND orders {"date":{"$gte": "2024-01-01","$lte": "2024-12-31"}}

# Paginated query
FIND users {"status": "active"} 0 10

# Sorted query
SORT users {"name": "John"} {"age": 1, "name": -1}

# Sorted + paginated query
SORT users {"name": "John"} {"age": 1, "name": -1} 0 10

# Single update
UPDATE users {"name": "John"} {"$set": {"age": 30}}

# Batch update
UPDATE products {"category": "electronics"} {"$inc": {"stock": -1}}

# Conditional update
UPDATE orders {"status": "pending"} {"$set": {"status": "processing"}}

# Conditional delete
REMOVE users {"status": "inactive"}

# Batch delete
REMOVE logs {"date": {"$lt": "2024-01-01"}}

This project is licensed under the MIT license.

©️ 2025 邱敬幃 Pardn Chiu