CovenantSQL
CovenantSQL is a decentralized SQL database management system derived from SQLite and built on top of a blockchain. It supports most of the SQL-92 features. Each party interacting with CovenantSQL is either a client, a block producer, or a miner:
- Client: A client supplies queries and wait for responses, which contain result sets of the queries.
- Block Producer: A block producer matches clients with miners and maintains metadata about the clients (e.g. query history, digital signature, etc.) and the miners (e.g. availability, computing power, etc.).
- Miner: A miner is a single database engine that serves both as a storage system and an execution engine. Miners register themselves with the block producers to indicate their desire to server clients.
When a client sends a connection request, the request is directed to one node among a group of block producers. The block producers maintain a public blockchain (main chain). When a block producer receives a request, it allocates a number of miners. The miners self-organize and produce a separate block chain, called a shard chain. Each miner is an independent database engine running SQLite. CovenantSQL uses Go's driver for SQLite to interact with individual miners.
The main chain implements Delegated Proof-of-Stake, which provides eventual consistency among block producers. The block producers pack all SQL queries from clients along with the shard chain's signature into the main block chain. The shard chains themselves consist of database contents and query results. The miners pertaining a shard chain use Byzantine Fault-Toleranted Raft, which provides strong consistency among miners that serve the same client. The leader in each miner group uses two phase commit to support transactions.
Checkpoints
Individual miners run SQLite.
Concurrency Control
Two-Phase Locking (Deadlock Prevention) Two-Phase Locking (Deadlock Detection)
Individual miners run SQLite.
Data Model
Individual miners run SQLite.
Foreign Keys
Individual miners run SQLite.
Indexes
Individual miners run SQLite.
Logging
Individual miners run SQLite.
Query Compilation
Individual miners run SQLite.
Query Execution
Individual miners run SQLite.
Query Interface
CovenantSQL supports the same set of standard SQLite commands.
Storage Architecture
Clients can specify the storage architecture through a parameter in the connection request to the database. Same as SQLite.
Stored Procedures
Same as SQLite.
System Architecture
CovenantSQL uses a three-level architecture, consisting of a main block chain, many shard chains, and individual miners. The main block chain is produced by a group of nodes called block producers, responsible for matching clients to shard chains. Each shard chain, which is produced by a designated group of computing nodes called miners, is a single database. Each miner is a standalone database engine that is responsible for storage and query processing. The miners reach consensus using a variant of Byzantine Fault-Tolerated Raft, which the developers call Kayak. When a leading miner goes offline, the miners in the same shard chain resort to a block producer to decide whether to wait for the leader to come back online or to elect a new leader. This is different from the original Raft, which handles changes in leader internally.
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Website
Source Code
https://github.com/CovenantSQL/CovenantSQL
Tech Docs
https://developers.covenantsql.io
Developer
Covenant Labs
Country of Origin
Start Year
2018
Project Type
Written in
Supported languages
Go, Java, JavaScript, Python, SQL