supabase/apps/docs/content/guides/database/extensions/plv8.mdx

---
id: 'plv8'
title: 'plv8: JavaScript Language'
description: 'JavaScript language for Postgres.'
---

<Admonition type="deprecation">

The `plv8` extension is deprecated in projects using Postgres 17. It continues to be supported in projects using Postgres 15, but will need to dropped before those projects are upgraded to Postgres 17. See the [Upgrading to Postgres 17 notes](/docs/guides/platform/upgrading#upgrading-to-postgres-17) for more information.

</Admonition>

The `plv8` extension allows you use JavaScript within Postgres.

## Overview

While Postgres natively runs SQL, it can also run other procedural languages.
`plv8` allows you to run JavaScript code - specifically any code that runs on the [V8 JavaScript engine](https://v8.dev).

It can be used for database functions, triggers, queries and more.

## Enable the extension

<Tabs
  scrollable
  size="small"
  type="underlined"
  defaultActiveId="dashboard"
  queryGroup="database-method"
>
<TabPanel id="dashboard" label="Dashboard">

1. Go to the [Database](/dashboard/project/_/database/tables) page in the Dashboard.
2. Click on **Extensions** in the sidebar.
3. Search for "plv8" and enable the extension.

</TabPanel>
<TabPanel id="sql" label="SQL">

```sql
-- Example: enable the "plv8" extension
create extension plv8;

-- Example: disable the "plv8" extension
drop extension if exists plv8;
```

Even though the SQL code is `create extension`, this is the equivalent of enabling the extension.
To disable an extension, call `drop extension`.

Procedural languages are automatically installed within `pg_catalog`, so you don't need to specify a schema.

</TabPanel>
</Tabs>

## Create `plv8` functions

Functions written in `plv8` are written like any other Postgres functions, only
with the `language` identifier set to `plv8`.

```sql
create or replace function function_name()
returns void as $$
    // V8 JavaScript
    // code
    // here
$$ language plv8;
```

You can call `plv8` functions like any other Postgres function:

<Tabs
  scrollable
  size="small"
  type="underlined"
  defaultActiveId="sql"
  queryGroup="language"
>
<TabPanel id="sql" label="SQL">

```sql
select function_name();
```

</TabPanel>
<TabPanel id="js" label="JavaScript">

```js
const { data, error } = supabase.rpc('function_name')
```

</TabPanel>
<$Show if="sdk:kotlin">
<TabPanel id="kotlin" label="Kotlin">

```kotlin
val data = supabase.postgrest.rpc("function_name")
```

</TabPanel>
</$Show>
</Tabs>

## Examples

### Scalar functions

A [scalar function](https://plv8.github.io/#scalar-function-calls) is anything that takes in some user input and returns a single result.

```sql
create or replace function hello_world(name text)
returns text as $$

    let output = `Hello, ${name}!`;
    return output;

$$ language plv8;
```

### Executing SQL

You can execute SQL within `plv8` code using the [`plv8.execute` function](https://plv8.github.io/#plv8-execute).

```sql
create or replace function update_user(id bigint, first_name text)
returns smallint as $$

    var num_affected = plv8.execute(
        'update profiles set first_name = $1 where id = $2',
        [first_name, id]
    );

    return num_affected;
$$ language plv8;
```

### Set-returning functions

A [set-returning function](https://plv8.github.io/#set-returning-function-calls) is anything that returns a full set of results - for example, rows in a table.

```sql
create or replace function get_messages()
returns setof messages as $$

    var json_result = plv8.execute(
        'select * from messages'
    );

    return json_result;
$$ language plv8;

select * from get_messages();
```

## Resources

- Official [`plv8` documentation](https://plv8.github.io/)
- [plv8 GitHub Repository](https://github.com/plv8/plv8)