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.

Enable the extension#

Create plv8 functions#

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

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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:

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select function_name();

Examples#

Scalar functions#

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

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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.

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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.

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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
• plv8 GitHub Repository