Clickhouse Utils
This crate provides a set of utilities for working with Clickhouse.
# Features
- fastnum: Enable support for Fastnum D256.
# Usage
## Migration
create a migrations folder in your project and add your migrations files.
Example:
```text
migrations/
├── 0001_create_users_table.sql
└── 0002_add_email_column.sql
```
Run the migrations:
```rust,no_run
#[tokio::main]
async fn main() {
let client = clickhouse::Client::default()
.with_user("default")
.with_password("default")
.with_url("http://localhost:8123")
.with_database("default");
clickhouse_utils::migrate(&client).await.expect("failed to run migrations");
}
```
## Serde
Serialize and Deserialize common types for Clickhouse.
- Std Hashmap of <String, String>
- Fastnum : any decimals with a fix size scale mandated by the clickhouse schema
## Examples
```rust,no_run
use std::collections::HashMap;
use serde::{Deserialize, Serialize};
use fastnum::decimal::D256;
#[derive(Debug, Serialize, Deserialize, clickhouse::Row)]
pub struct SomeTable {
#[serde(with = "clickhouse_utils::serde::fastnum::Decimal::<25, {256 / 64}>")]
pub decimal: D256,
#[serde(with = "clickhouse_utils::serde::map")]
pub attributes: HashMap<String, String>,
}
```
For the decimal fastnum::D256, we use:
- Decimal with { 256 / 64 } or Uint<4>
- 25 decimals, that should corelate with you clickhouse schema
The database schema used:
```sql
CREATE TABLE clickhouse_utils (
decimal Decimal256(25),
attributes Map(String, String),
) ENGINE = MergeTree()
ORDER BY (decimal)
```