[docs] Add docs for flink materialized table

Author: 风离

website/docs/engine-flink/ddl.md

@@ -273,3 +273,106 @@ ALTER TABLE my_multi_fields_part_log_table DROP PARTITION (dt = '2025-03-05', na
 ```
 
 For more details, refer to the [Flink ALTER TABLE(DROP)](https://nightlies.apache.org/flink/flink-docs-release-1.20/docs/dev/table/sql/alter/#drop) documentation.
+
+## Materialized Table
+### Overview
+Flink Materialized Table is a new table type introduced in Flink SQL, aimed at simplifying both batch and stream data pipelines, providing a consistent development experience. By specifying data freshness and query when creating Materialized Table, the engine automatically derives the schema for the materialized table and creates corresponding data refresh pipeline to achieve the specified freshness.
+For more details, refer to the [Flink Materialized Table](https://nightlies.apache.org/flink/flink-docs-release-2.1/docs/dev/table/materialized-table/overview/).
+
+Starting from Fluss version 0.8, Flink Materialized Table is now supported, which can significantly reduce the cost of building real-time data pipelines with Flink + Fluss. Materialized tables in Fluss are implemented as regular Fluss tables with special metadata to identify them as materialized tables.
+
+### Create Materialized Table
+
+Materialized tables are created using the `CREATE MATERIALIZED TABLE` statement with a freshness interval and a query definition:
+
+```sql title="Flink SQL"
+CREATE MATERIALIZED TABLE shop_summary
+FRESHNESS = INTERVAL '5' SECOND
+AS SELECT 
+  DATE_FORMAT(order_time, 'yyyy-MM-dd') AS order_date,
+  shop_id,
+  COUNT(*) AS order_count,
+  SUM(amount) AS total_amount
+FROM orders
+GROUP BY DATE_FORMAT(order_time, 'yyyy-MM-dd'), shop_id;
+```
+
+#### Supported Refresh Mode
+
+Fluss currently supports **CONTINUOUS** refresh mode for materialized table, which means the materialized table is continuously refreshed. The **FULL** refresh mode will be supported in future releases.
+
+#### Schema Definition
+
+The schema of a materialized table is automatically inferred from the query definition. You cannot manually specify column names and types - they are derived from the SELECT statement.
+
+```sql title="Flink SQL"
+-- The schema will be automatically inferred as:
+-- order_date: STRING
+-- shop_id: BIGINT  
+-- order_count: BIGINT
+-- total_amount: BIGINT
+CREATE MATERIALIZED TABLE daily_sales
+FRESHNESS = INTERVAL '1' MINUTE
+AS SELECT 
+  DATE_FORMAT(created_at, 'yyyy-MM-dd') AS order_date,
+  shop_id,
+  COUNT(*) AS order_count,
+  SUM(amount) AS total_amount
+FROM sales_events
+GROUP BY DATE_FORMAT(created_at, 'yyyy-MM-dd'), shop_id;
+```
+
+### Alter Materialized Table
+
+You can suspend and resume materialized tables to control their refresh behavior:
+
+#### Suspend Materialized Table
+
+```sql title="Flink SQL"
+ALTER MATERIALIZED TABLE shop_summary SUSPEND;
+```
+
+This stops the automatic refresh of the materialized table and saves the current state.
+
+#### Resume Materialized Table
+
+```sql title="Flink SQL"
+ALTER MATERIALIZED TABLE shop_summary RESUME;
+```
+
+This resumes the automatic refresh of the materialized table from the last saved state.
+
+### Drop Materialized Table
+
+To delete a materialized table:
+
+```sql title="Flink SQL"
+DROP MATERIALIZED TABLE shop_summary;
+```
+
+This will drop the materialized table and stop the background refresh job.
+
+### Materialized Table Options
+
+Materialized tables support the same table options as regular Fluss tables, including partitioning and bucketing:
+
+```sql title="Flink SQL"
+CREATE MATERIALIZED TABLE partitioned_summary
+FRESHNESS = INTERVAL '10' SECOND
+AS SELECT 
+  dt,
+  shop_id,
+  COUNT(*) AS order_count
+FROM orders
+GROUP BY dt, shop_id
+PARTITIONED BY (dt)
+WITH (
+  'bucket.num' = '4'
+);
+```
+
+### Limitations
+
+- Only continuous refresh mode is supported
+- Schema is automatically derived from the query
+- Materialized tables are stored as regular Fluss tables with special metadata

website/docs/engine-flink/getting-started.md

@@ -28,6 +28,9 @@ For Flink's Table API, Fluss supports the following features:
 | [SQL create table](ddl.md#create-table)           | ✔️    |                                        |
 | [SQL create table like](ddl.md#create-table-like) | ✔️    |                                        |
 | [SQL drop table](ddl.md#drop-table)               | ✔️    |                                        |
+| [SQL create materialized table](ddl.md#materialized-table) | ✔️    | Continuous refresh mode only |
+| [SQL alter materialized table](ddl.md#alter-materialized-table) | ✔️    | Suspend/Resume support |
+| [SQL drop materialized table](ddl.md#drop-materialized-table) | ✔️    |                                        |
 | [SQL show partitions](ddl.md#show-partitions)     | ✔️    |                                        |
 | [SQL add partition](ddl.md#add-partition)         | ✔️    |                                        |
 | [SQL drop partition](ddl.md#drop-partition)       | ✔️    |                                        |