TiKV Client (Rust)

Currently this crate is experimental and some portions (e.g. the Transactional API) are still in active development. You're encouraged to use this library for testing and to help us find problems!

Docs

This crate provides a clean, ready to use client for TiKV, a distributed transactional Key-Value database written in Rust.

With this crate you can easily connect to any TiKV deployment, interact with it, and mutate the data it contains. It uses async/await internally and exposes some async fn APIs as well.

This is an open source (Apache 2) project hosted by the Cloud Native Computing Foundation (CNCF) and maintained by the TiKV Authors. We'd love it if you joined us in improving this project.

Getting started

The TiKV client is a Rust library (crate). To use this crate in your project, add following dependencies in your Cargo.toml:

[dependencies]
tikv-client = { git = "https://github.com/tikv/client-rust.git" }

The client requires a Git dependency until we can publish it.

The client provides two modes to interact with TiKV: raw and transactional. In the current version (0.0.0), the transactional API supports optimistic transactions. Pessimistic transactions are implemented but not well tested.

Important note: It is not recommended or supported to use both the raw and transactional APIs on the same database.

Code examples

Raw mode:

let config = Config::new(vec!["127.0.0.1:2379"]);
let client = RawClient::new(config).await?;
client.put("key".to_owned(), "value".to_owned()).await;
let value = client.get("key".to_owned()).await;

Transactional mode:

let config = Config::new(vec!["127.0.0.1:2379"]);
let txn_client = TransactionClient::new(config).await?;
let mut txn = txn_client.begin().await?;
txn.put("key".to_owned(), "value".to_owned()).await?;
let value = txn.get("key".to_owned()).await;
txn.commit().await?;

There are some examples which show how to use the client in a Rust program.

API

Raw requests

Request	Main parameter type	Successful result type	Noteworthy Behavior
put	KvPair	()
get	Key	Option<Value>
delete	Key	()
scan	BoundRange	Vec<KvPair>
batch_put	Iter<KvPair>	()
batch_get	Iter<Key>	Vec<KvPair>	Skip non-existent keys; Does not retain order
batch_delete	Iter<Key>	()
delete_range	BoundRange	()

Transactional requests

Request	Main parameter type	Successful result type	Noteworthy Behavior
put	KvPair	()
get	Key	Option<value>
delete	Key	()
scan	BoundRange	Iter<KvPair>
batch_get	Iter<Key>	Iter<KvPair>	Skip non-existent keys; Does not retain order
lock_keys	KvPair	()
gc	Timestamp	bool	It returns whether the latest safepoint in PD equals the parameter

For detailed behavior of each request, please refer to the doc.

Experimental raw requests

You must be careful if you want to use the following request(s). Read the description for reasons.

Request	Main parameter type	Successful result type
batch_scan	Iter<BoundRange>	Vec<KvPair>

The each_limit parameter does not work as expected. It does not limit the number of results returned of each range, instead it limits the number of results in each region of each range. As a result, you may get more than each_limit key-value pairs for each range. But you should not miss any entries.

The results of batch_scan are flattened. The order of ranges is retained.

Useful types

To use the client, there are 4 types you will need.

Key is simply a vector of bytes(Vec<u8>). String and Vec<u8> implements Into<Key>, so you can directly pass them to clients.

Value is just an alias of Vec<u8>.

KvPair is a tuple consisting of a Key and a Value. It also provides some convenience methods for conversion to and from other types.

BoundRange is used for range related requests like scan. It implements From for usual ranges so you can just create a range and pass them to the request.For instance, client.scan("k2".to_owned()..="k5".to_owned(), 5) or client.delete_range(vec![]..).

Access the documentation

We've done our best to include ample, tested, and understandable examples.

We recommend using the officially maintained documentation here.

You can also access the documentation on your machine by running the following in any project that depends on tikv-client.

cargo doc --package tikv-client --open
# If it didn't work, browse file URL it tried to open with your browser.

Minimal Rust version

This crate supports Rust 1.40 and above.

For development, a nightly Rust compiler is needed to compile the tests.