--- title: "Realtime | SurrealDB" description: "Subscribe to queries with LIVE SELECT, react to writes with DEFINE EVENT, and stream mutations with changefeeds - realtime built into the database." url: https://surrealdb.com/surrealdb/realtime --- REALTIME # Realtime, built in Subscribe to a query and receive every change as it commits. LIVE SELECT turns any query into a realtime feed over WebSockets, DEFINE EVENT runs server-side logic on writes, and changefeeds give you an ordered, durable stream of mutations - no message broker to run alongside the database. [Read the docs](https://surrealdb.com/docs/reference/query-language/statements/live-select) [Start free with SurrealDB](https://studio.surrealdb.com/current/instances/deploy) 1. ![Babcock](https://surrealdb.com/assets/static/babcock.lo4rnVg1.svg) 2. ![ING](https://surrealdb.com/assets/static/ing.X3I6S3_V.svg) 3. ![British Airways](https://surrealdb.com/assets/static/british-airways.KEsZiwV-.svg) 4. ![Nvidia](https://surrealdb.com/assets/static/nvidia.DaIEuMil.svg) 5. ![Apple](https://surrealdb.com/assets/static/apple.D5pq4flY.svg) 6. ![SpaceX](https://surrealdb.com/assets/static/spacex.CQJEk-IL.svg) 7. ![Samsung](https://surrealdb.com/assets/static/samsung.CH-vQgnb.svg) 8. ![adidas](https://surrealdb.com/assets/static/adidas.DdTC5qhk.svg) 9. ![Tencent](https://surrealdb.com/assets/static/tencent.paQmLxyy.svg) 10. ![Alibaba](https://surrealdb.com/assets/static/alibaba.B16idgfM.svg) 11. ![PolyAI](https://surrealdb.com/assets/static/poly-ai.c3w_fAg6.svg) 12. ![Later](https://surrealdb.com/assets/static/later.Ds736jFO.svg) 13. ![Verizon](https://surrealdb.com/assets/static/verizon.BI7CajdX.svg) 14. ![Liberty Mutual](https://surrealdb.com/assets/static/liberty-mutual.B7qOU1pd.svg) 15. ![Walmart](https://surrealdb.com/assets/static/walmart.BjDg_Sr8.svg) 16. ![Carrier](https://surrealdb.com/assets/static/carrier.D21gC6NX.svg) 17. ![Saks Fifth Avenue](https://surrealdb.com/assets/static/saks-fifth-avenue.COIDpLSb.svg) 18. ![San Francisco Compute Company](https://surrealdb.com/assets/static/sfcc.B7jlImq4.svg) 19. ![Shield AI](https://surrealdb.com/assets/static/shield-ai.pINZ0KJr.svg) 20. ![Wix](https://surrealdb.com/assets/static/wix.DvHhmoBi.svg) 01 |LIVE QUERIES ## Any query can become a subscription Add LIVE to a SELECT and the same filter, permissions, and shape you already use stream to the client on every matching change - full records or just the diff. ``` LIVE SELECT * FROM message WHERE channel = $auth.channel;-- The client receives each matching change as it commits:-- { action: "CREATE", result: { id: message:9f2, text: "hi" } }-- { action: "UPDATE", result: { id: message:9f2, text: "hey" } }-- { action: "DELETE", result: { id: message:9f2 } } ``` LIVE SELECT ## Subscribe with the query you already wrote A live query carries the same WHERE clause and permissions as a normal one. The client receives new, updated, and deleted records as they commit. ``` LIVE SELECT * FROM document WHERE account = $auth.account OR public = true;-- Stream only what changed, not the whole recordLIVE SELECT DIFF FROM task WHERE status != "closed";-- Stop receiving updatesKILL "0189d1af-8f1c-7f3a-9d4e-2c1b6a5e0f77"; ``` EVENTS AND CHANGEFEEDS ## React on write, replay on demand DEFINE EVENT runs logic in the engine when data changes; a changefeed keeps an ordered, durable record of mutations you can replay from any point. ``` DEFINE TABLE product CHANGEFEED 7d;SHOW CHANGES FOR TABLE product SINCE d"2024-01-01T00:00:00Z" LIMIT 100; ``` ## Reactive data without a broker Subscriptions, triggers, and durable change streams are part of the engine - so realtime is a query, not a second system to run. ### [Live queries](https://surrealdb.com/docs/reference/query-language/statements/live-select) Turn any SELECT into a realtime subscription over WebSockets, with the same filters and permissions. Learn more ### [Full records or diffs](https://surrealdb.com/surrealdb/features#database-engine) Receive the whole updated record, or only the changeset, to keep payloads small on high-frequency feeds. Learn more ### [Server-side events](https://surrealdb.com/surrealdb/features#database-engine) DEFINE EVENT runs logic in the database when data changes - validation, fan-out, and derived writes. Learn more ### [Changefeeds](https://surrealdb.com/surrealdb/features#database-engine) An ordered, durable stream of mutations per table, replayable from any point in the retention window. Learn more ### [Filtered subscriptions](https://surrealdb.com/docs/reference/query-language/statements/live-select) Subscribe to one record, a filtered set, or a whole table - and to graph-joined shapes across relationships. Learn more ### [Permissions apply live](https://surrealdb.com/surrealdb/auth) Row-level rules govern subscriptions too, so a client only ever streams the records it is allowed to see. Learn more 02 |ONE ENGINE ## No message broker in the middle The usual realtime stack polls the database, or wires a broker and a change-data-capture pipeline beside it. SurrealDB pushes changes from the engine that made them. ### No polling Clients subscribe once and the engine pushes changes as they commit, instead of re-querying on a timer and hoping to catch updates. ### No separate pipeline Live queries and changefeeds come from the database itself - there is no broker, CDC connector, or stream processor to deploy and keep in sync. ### Consistent with the write Updates are emitted by the transaction that made them, so subscribers see exactly what committed, in order. ## Keep exploring ### [Live query documentation](https://surrealdb.com/docs/reference/query-language/statements/live-select) LIVE SELECT, DIFF, and KILL in full. Explore ### [Real-time use case](https://surrealdb.com/use-cases/real-time) Patterns for reactive applications on SurrealDB. Explore ### [All features](https://surrealdb.com/surrealdb/features#database-engine) Live queries, events, and changefeeds in the feature set. Explore GET STARTED ## Make your data reactive Subscribe with LIVE SELECT, react with DEFINE EVENT, and stream changes - all from SurrealDB. ![Samsung](https://surrealdb.com/assets/static/4c58b81e7b3c9466.C_Hv0eml.svg)![NVIDIA](https://surrealdb.com/assets/static/nvidia.DaIEuMil.svg)![Apple](https://surrealdb.com/assets/static/f7dc2519e0d212bc.Cn8MYAK7.svg)![Verizon](https://surrealdb.com/assets/static/18b99996c689000f.B5PQ-nI9.svg)![Tencent](https://surrealdb.com/assets/static/401d8346058682c8.DqM87mst.svg) SOC 2 Type 2 GDPR Cyber Essentials Plus ISO 27001 [Read the docs](https://surrealdb.com/docs/reference/query-language/statements/live-select) [Start free with SurrealDB](https://studio.surrealdb.com/current/instances/deploy) ```json {"@context":"https://schema.org","@type":"Organization","name":"SurrealDB","url":"https://surrealdb.com","logo":"https://surrealdb.com/assets/static/logo.BG7_TG2b.svg","description":"SurrealDB is the unified data layer for AI. 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