# Live queries

Subscribing to inserts, updates, and deletes with LIVE SELECT so clients stay in sync over a persistent connection.

Live queries are SurrealDB's way to push changes to a client. Running a `LIVE SELECT` opens a subscription that sends notifications whenever matching records appear, change, or disappear, without needing to directly poll the database to do so.

That fits interactive UIs, dashboards, and small collaboration features. For replaying history or catching up a batch pipeline, use [changefeeds](/docs/learn/querying/real-time/changefeeds.md) and `SHOW CHANGES` instead.

The full grammar and edge cases live under [`LIVE SELECT`](/docs/reference/query-language/statements/live-select.md) in the reference. Below is how to think about subscriptions and what to watch for in production.

## Starting a subscription

By default, creates and updates deliver the full record; deletes return nothing unless you add a clause like `RETURN BEFORE`. You receive a UUID as soon as the live query is registered. This UUID can later be passed in to a [`KILL`](/docs/reference/query-language/statements/kill.md) statement when you want to stop.

```surql
LIVE SELECT * FROM person;

-- u'b1f1d115-ad0f-460d-8cbf-dbc7ce48851c'
```

Message layout on the wire is described in the [live query / WebSocket protocol](/docs/reference/rest-api/rpc-protocol.md#live-websocket-only) section.

## DIFF mode

If you prefer patches instead of whole documents on update, use `DIFF`. Updates arrive as [JSON Patch](https://jsonpatch.com/)-style arrays, which can be smaller and easier to merge on the client when records are large.

```surql
LIVE SELECT DIFF FROM person;

-- 'b87cbb0d-ca15-4f0a-8f86-caa680672aa5'
```

## Filtering with WHERE

You can narrow the subscription the same way you would a normal `SELECT`: only rows that match your predicate participate.

```surql
LIVE SELECT * FROM person WHERE age > 18;
```

## Consistency and security

Notifications reflect committed work, so a live event will not take place if a transaction is rolled back.

Under heavy concurrency, the system makes a best effort to preserve sensible ordering, but you should not assume a total order across all writers that matches commit order in every edge case.

## Parameters in live queries

From v3.0.0 onwards you can use session parameters in live queries, such as by binding names with `LET` before you open the subscription.

```surql
LET $table = 'measurement';
LET $location = 'Tallinn';
LIVE SELECT * FROM type::table($table) WHERE location == $location;
```

## Where to read more

* [`LIVE SELECT` reference](/docs/reference/query-language/statements/live-select.md)
* [Changefeeds](/docs/learn/querying/real-time/changefeeds.md) - replay and `SHOW CHANGES`
* [Real-time best practices](/docs/learn/querying/real-time/real-time-best-practices.md) - wider event-driven patterns