# SSDB — Fast NoSQL Database as a Redis Alternative

> A high-performance NoSQL database supporting Redis-compatible commands with persistent storage on LevelDB, designed for large datasets that exceed memory.

## Install

Save as a script file and run:

# SSDB — Fast NoSQL Database as a Redis Alternative

## Quick Use
```bash
wget https://github.com/ideawu/ssdb/archive/master.zip
unzip master.zip && cd ssdb-master
make
./ssdb-server ssdb.conf

# Connect with the built-in CLI
./tools/ssdb-cli -p 8888
ssdb> set mykey hello
ssdb> get mykey
```

## Introduction
SSDB is a high-performance NoSQL database written in C++ that provides Redis-compatible commands backed by LevelDB or RocksDB for persistent storage. It is designed for datasets too large to fit in memory, offering disk-based storage with performance close to Redis for common operations.

## What SSDB Does
- Stores key-value, hash, sorted set, list, and queue data structures
- Supports a large subset of Redis commands for easy migration
- Persists data to disk using LevelDB or RocksDB storage engines
- Handles datasets far exceeding available RAM via disk-backed storage
- Provides master-slave and master-master replication

## Architecture Overview
SSDB uses a single-threaded event loop for network I/O and dispatches storage operations to LevelDB or RocksDB. Data structures are encoded into key-value pairs in the underlying LSM-tree engine. Write-ahead logging ensures durability, and background compaction keeps read performance stable. The replication system streams binlog entries between nodes for high availability.

## Self-Hosting & Configuration
- Build from source with make on Linux or macOS
- Edit ssdb.conf to set the listen port, data directory, and cache size
- Configure LevelDB cache and block size for your workload
- Set up master-slave replication by adding slaveof directives
- Monitor with the built-in info command or compatible Redis tools

## Key Features
- Redis-compatible API supporting most common data structure commands
- Disk-based storage handling hundreds of GB without memory constraints
- Master-slave and master-master replication for high availability
- LevelDB and RocksDB backend options for tuning write amplification
- Clients available in most programming languages (Python, Go, Java, PHP, Node.js)

## Comparison with Similar Tools
- **Redis** — in-memory only (without persistence add-ons); SSDB stores data on disk for larger-than-RAM datasets
- **KeyDB** — multithreaded Redis fork still memory-bound; SSDB is disk-native
- **Pika** — another Redis-on-disk alternative using RocksDB; SSDB offers a simpler, lighter deployment
- **DragonflyDB** — modern in-memory store; SSDB targets scenarios where data must persist on disk

## FAQ
**Q: Can I use existing Redis clients with SSDB?**
A: Yes, SSDB supports the Redis wire protocol for most commands. Standard Redis clients in Python, Go, Java, and other languages work with minor adjustments.

**Q: How does performance compare to Redis?**
A: For datasets that fit in the OS page cache, SSDB approaches Redis speeds. For larger datasets, disk I/O becomes the bottleneck but remains fast thanks to LevelDB optimizations.

**Q: Does SSDB support clustering?**
A: SSDB supports master-slave and master-master replication. Application-level sharding is used for horizontal scaling across multiple instances.

**Q: What happens if the server crashes?**
A: LevelDB provides write-ahead logging. On restart, SSDB recovers committed data automatically from the WAL and SST files.

## Sources
- https://github.com/ideawu/ssdb
- http://ssdb.io/

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Source: https://tokrepo.com/en/workflows/asset-e5aaa904
Author: Script Depot