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147 lines
3.2 KiB
Plaintext
147 lines
3.2 KiB
Plaintext
---
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id: plv8
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title: 'plv8: JavaScript Language'
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description: JavaScript language for PostgreSQL.
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---
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import Tabs from '@theme/Tabs'
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import TabItem from '@theme/TabItem'
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The `plv8` extension allows you use JavaScript within Postgres.
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## Overview
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While Postgres natively runs SQL, it can also run other "procedural languages".
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`plv8` allows you to run JavaScript code - specifically any code that runs on the [V8 JavaScript engine](https://v8.dev).
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It can be used for database functions, triggers, queries and more.
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## Usage
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### Enable the extension
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<Tabs
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defaultValue="dashboard"
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values={[
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{label: 'Dashboard', value: 'dashboard'},
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{label: 'SQL', value: 'sql'},
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]}>
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<TabItem value="dashboard">
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1. Go to the [Database](https://app.supabase.com/project/_/database/tables) page in the Dashboard.
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2. Click on **Extensions** in the sidebar.
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3. Search for "plv8" and enable the extension.
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</TabItem>
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<TabItem value="sql">
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```sql
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-- Example: enable the "plv8" extension
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create extension plv8;
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-- Example: disable the "plv8" extension
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drop extension if exists plv8;
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```
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Even though the SQL code is `create extension`, this is the equivalent of "enabling the extension".
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To disable an extension, call `drop extension`.
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Procedural languages are automatically installed within `pg_catalog`, so you don't need to specify a schema.
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</TabItem>
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</Tabs>
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### Create `plv8` functions
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Functions written in `plv8` are written just like any other PostgreSQL functions, only
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with the `language` identifier set to `plv8`.
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```sql
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create or replace function function_name()
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returns void as $$
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// V8 JavaScript
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// code
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// here
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$$ language plv8;
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```
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You can call `plv8` functions like any other Postgres function:
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<Tabs
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defaultValue="sql"
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values={[
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{label: 'SQL', value: 'sql'},
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{label: 'JavaScript', value: 'javascript'},
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]}>
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<TabItem value="sql">
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```sql
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select function_name();
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```
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</TabItem>
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<TabItem value="javascript">
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```js
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const { data, error } = supabase.rpc('function_name')
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```
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</TabItem>
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</Tabs>
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## Examples
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### Scalar functions
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A [scalar function](https://plv8.github.io/#scalar-function-calls) is anything that takes in some user input and returns a single result.
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```sql
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create or replace function hello_world(name text)
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returns text as $$
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let output = `Hello, ${name}!`;
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return output;
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$$ language plv8;
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```
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### Executing SQL
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You can execute SQL within `plv8` code using the [`plv8.execute` function](https://plv8.github.io/#plv8-execute).
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```sql
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create or replace function update_user(id bigint, first_name text)
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returns smallint as $$
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var num_affected = plv8.execute(
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'update profiles set first_name = $1 where id = $2',
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[first_name, id]
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);
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return num_affected;
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$$ language plv8;
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```
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### Set-returning functions
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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.
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```sql
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create or replace function get_messages()
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returns setof messages as $$
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var json_result = plv8.execute(
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'select * from messages'
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);
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return json_result;
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$$ language plv8;
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```
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## Resources
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- Official [`plv8` documentation](https://plv8.github.io/)
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- [plv8 GitHub Repository](https://github.com/plv8/plv8)
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