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plv8: Javascript Language

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.

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

Usage#

Enabling#

1. Go to the Database page.
2. Click on "Extensions" in the sidebar.
3. Search for "plv8".
4. Click the toggle.

Creating plv8 functions#

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

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:

select function_name();

Examples#

Scalar Functions#

A scalar function is anything that takes in some user input and returns a single result.

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.

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 is anything that returns a full set of results - for example, rows in a table.

create or replace function get_messages()
returns setof messages as $$
var json_result = plv8.execute(
'select * from messages'
);
return json_result;
$$ language plv8;

Resources#