https://github.com/metrico/clickhouse-udf-vlang
Example vlang UDF for Clickhouse
https://github.com/metrico/clickhouse-udf-vlang
clickhouse cloki udf user-defined-function v vlang
Last synced: 7 months ago
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Example vlang UDF for Clickhouse
- Host: GitHub
- URL: https://github.com/metrico/clickhouse-udf-vlang
- Owner: metrico
- Created: 2022-03-13T12:26:47.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2022-09-24T17:22:22.000Z (almost 4 years ago)
- Last Synced: 2025-05-19T23:08:38.579Z (about 1 year ago)
- Topics: clickhouse, cloki, udf, user-defined-function, v, vlang
- Language: V
- Homepage:
- Size: 21.5 KB
- Stars: 4
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# V ClickHouse UDF
> ClickHouse can call any external executable program or script to process data.
This basic example illustrates a simple `sum` [V](https://vlang.io/) powered function for [Clickhouse UDF](https://clickhouse.com/docs/en/sql-reference/functions/#executable-user-defined-functions) usage
### V Function
To get started, create an baseline vlang application with the following features:
- [x] read input from stdin
- [x] parse tab separated columns
- [ ] do something with data
- [x] return some output
Here's an example `sum` function:
```
import os
fn main() {
// Parse stdin to array
data := os.get_lines()
for line in data {
// split tabSeparated columns
columns := line.split('\t')
// sum two integers
sum := columns[0].int() + columns[1].int()
// return a result
println(sum)
}
}
```
Compile and store into the ClickHouse UDF script directory:
```
v -o /var/lib/clickhouse/user-scripts/vlang-udf -prod .
```
The final static executable size is < ~100KB all inclusive!
```
-rwxr-xr-x 1 root root 98K Mar 13 12:49 vlang-udf*
```
### ClickHouse UDF
Create a [UDF Function XML](https://clickhouse.com/docs/en/sql-reference/functions/#executable-user-defined-functions) to invoke your vlang binary
Define the _input and output_ [format](https://clickhouse.com/docs/en/interfaces/formats) our function requires _(UInt64, string, etc)_
```
executable
v_sum
UInt64
UInt64
UInt64
TabSeparated
vlang-udf
0
```
> MUST use directory `/var/lib/clickhouse/user-scripts` to store both user-scripts and executable udf
### Usage
```
SELECT v_sum(10, 20)
Query id: f98a5f83-4e94-41d0-9d9f-78b37d3af152
┌─v_sum(10, 20)─────┐
│ 30 │
└───────────────────┘
1 rows in set. Elapsed: 0.006 sec.
```
That's all it takes! Go create your superfast v powered UDF function for fun and profit!