# Database extensions (pgvector, PostGIS …)

`list_extensions { ref }` returns the extensions you can turn on and their state (available, enabled, version).
Turn one on with `enable_extension { ref, name }` and off with `disable_extension { ref, name, confirm: name }`.
Only owners and admins can turn them on and off.

What you can turn on: `vector` (pgvector), `postgis`, `citext`, `hstore`, `uuid-ossp`, `pgcrypto`,
`ltree`, `fuzzystrmatch`, `btree_gin`, `btree_gist`, `intarray`, `tablefunc`.
`pg_trgm` and `unaccent` are on from the start and cannot be turned off. Extensions not on the list are refused.

Extensions are installed in the `extensions` schema, and that schema is on every search path (the SQL editor, direct connections, the data API),
so you use them without a schema prefix.

```sql
-- after enable_extension { ref, name: "vector" }
create table docs (id bigserial primary key, body text, embedding vector(1536));
create index if not exists docs_embedding_hnsw on docs using hnsw (embedding vector_cosine_ops);
select id, body from docs order by embedding <=> '[...]' limit 5;

-- after enable_extension { ref, name: "postgis" }
create table places (id bigserial primary key, name text, at geography(point, 4326));
select name from places where st_dwithin(at, st_makepoint(126.978, 37.566)::geography, 1000);
```

To find the nearest rows through the data API, write a function and call it with `POST /rest/v1/rpc/<function>`.

**On a shared database, an extension belongs to the whole database.** If another project has turned on the same extension,
turning it off leaves it installed (`note`) and only removes this project's record. While columns, indexes or functions
that use the extension remain, turning it off is refused. Remove those first.

Over HTTP it is `GET /extensions`, `PUT /extensions/<name>` (on) and `DELETE /extensions/<name>` (off).

---

https://end.blackall.ai/docs/extensions?lang=en