TiDB

TiDB is an open-source, distributed SQL database written in Go. It speaks the MySQL 8.0 wire protocol, stores data in a horizontally scalable key-value layer (TiKV) with Raft replication, and supports both transactional (OLTP) and analytical (HTAP via TiFlash) workloads from the same data.

This repository (github.com/pingcap/tidb) contains the TiDB SQL layer: the parser, planner/optimizer, execution engine, schema and DDL machinery, session and protocol handling, statistics, and the storage client that talks to TiKV/PD. It also hosts several first-party CLI tools that ship alongside the database server: BR (backup & restore), Lightning (bulk data import), and Dumpling (logical export).

What this repo contains

• cmd/tidb-server/ — the TiDB SQL server entry point (main.go).
• pkg/ — the bulk of the database. Parser, planner, executor, expression engine, DDL, infoschema, sessions, statistics, storage client, server (MySQL protocol), domain (metadata cache and lifecycle), and a large util/ tree.
• br/ — Backup & Restore tool and library.
• lightning/ — TiDB Lightning (high-throughput SQL/CSV import).
• dumpling/ — Dumpling (logical SQL/CSV dump tool).
• tests/ — integration and real-TiKV test harnesses (integrationtest, realtikvtest, clusterintegrationtest, globalkilltest, …).
• docs/ — architecture index, agent runbooks, and design docs.
• tools/ — repo tooling (e.g., tools/check, tools/tazel, tools/patch-go).

Where to start reading

• New to TiDB → Architecture and the Getting started guide.
• Looking up a SQL- or storage-specific concept → Glossary.
• About to contribute → How to contribute and Patterns and conventions.
• Looking for a subsystem → see the Systems index and the source-of-truth docs/agents/architecture-index.md in the repo.

Where TiDB fits

A TiDB cluster has three core components:

• TiDB server (this repo): stateless SQL frontend.
• TiKV: distributed transactional KV store (separate repo: tikv/tikv).
• PD (Placement Driver): cluster metadata, region/leader scheduling, timestamp oracle (separate repo: tikv/pd).

Optionally, TiFlash provides a columnar replica for HTAP workloads. The TiDB server in this repo connects to TiKV and PD through the tikv/client-go/v2 Go client (see pkg/store/driver/), and to TiFlash through MPP coprocessor RPCs (see pkg/store/copr/).

License and project home

• License: Apache 2.0 (LICENSE).
• Documentation: https://docs.pingcap.com/tidb/stable.
• Issues and PRs: https://github.com/pingcap/tidb.
• Contributor guide: https://pingcap.github.io/tidb-dev-guide/.