Connect Streamlit to TiDB

Introduction

This guide explains how to securely access a remote TiDB database from Streamlit Community Cloud. It uses the mysqlclient library and Streamlit's secrets management. TiDB is an open-source, MySQL-compatible database that supports Hybrid Transactional and Analytical Processing (HTAP) workloads.

Sign in to TiDB Cloud and create a cluster

First, head over to TiDB Cloud and sign up for a free account, using either Google, GitHub or E-mail:

Once you've signed in, you can create a cluster:

Choose a cluster tier

Configure cluster specifications

Your screen should list the cluster you created. Click Security Settings to set the root password to access the cluster.

List clusters

Set password

Then click Connect to easily get the connnection arguments to access the cluster.

Create a TiDB database

Once your TiDB cluster is up and running, connect to it with the mysql client and enter the following commands to create a database and a table with some example values:

CREATE DATABASE pets;

USE pets;

CREATE TABLE mytable (
    name            varchar(80),
    pet             varchar(80)
);

INSERT INTO mytable VALUES ('Mary', 'dog'), ('John', 'cat'), ('Robert', 'bird');

Add username and password to your local app secrets

Your local Streamlit app will read secrets from a file .streamlit/secrets.toml in your app's root directory. Create this file if it doesn't exist yet and add the database name, user, and password of your TiDB cluster as shown below:

# .streamlit/secrets.toml

[tidb]
host = "<TiDB_cluster_endpoint>"
port = 4000
database = "pets"
user = "<TiDB_cluster_user>"
password = "<TiDB_cluster_password>"
ssl-ca = "<path_to_CA_store>"

Copy your app secrets to the cloud

As the secrets.toml file above is not committed to GitHub, you need to pass its content to your deployed app (on Streamlit Community Cloud) separately. Go to the app dashboard and in the app's dropdown menu, click on Edit Secrets. Copy the content of secrets.toml into the text area. More information is available at Secrets Management.

Add mysqlclient to your requirements file

Add the mysqlclient package to your requirements.txt file, preferably pinning its version (replace x.x.x with the version you want installed):

# requirements.txt
mysqlclient==x.x.x

Write your Streamlit app

Copy the code below to your Streamlit app and run it. Make sure to adapt query to use the name of your table.

# streamlit_app.py

import MySQLdb
import streamlit as st

# Initialize connection.
# Uses st.experimental_singleton to only run once.
@st.experimental_singleton
def init_connection():
    config = st.secrets["tidb"]
    return MySQLdb.connect(
        host=config["host"],
        port=config["port"],
        user=config["user"],
        password=config["password"],
        database=config["database"],
        ssl_mode="VERIFY_IDENTITY",
        ssl={"ca": config["ssl-ca"]}
    )

conn = init_connection()

# Perform query.
# Uses st.experimental_memo to only rerun when the query changes or after 10 min.
@st.experimental_memo(ttl=600)
def run_query(query):
    with conn.cursor() as cur:
        cur.execute(query)
        return cur.fetchall()

rows = run_query("SELECT * from mytable;")

# Print results.
for row in rows:
    st.write(f"{row[0]} has a :{row[1]}:")

See st.experimental_memo above? Without it, Streamlit would run the query every time the app reruns (e.g. on a widget interaction). With st.experimental_memo, it only runs when the query changes or after 10 minutes (that's what ttl is for). Watch out: If your database updates more frequently, you should adapt ttl or remove caching so viewers always see the latest data. Read more about caching here.

If everything worked out (and you used the example table we created above), your app should look like this: