add lance doc

Author: xx789633

website/docs/streaming-lakehouse/integrate-data-lakes/lance.md

@@ -0,0 +1,110 @@
+---
+title: Lance
+sidebar_position: 1
+---
+
+# Lance
+
+[Apache Paimon](https://paimon.apache.org/) innovatively combines a lake format with an LSM (Log-Structured Merge-tree) structure, bringing efficient updates into the lake architecture. 
+To integrate Fluss with Lance, you must enable lakehouse storage and configure Lance as the lakehouse storage. For more details, see [Enable Lakehouse Storage](maintenance/tiered-storage/lakehouse-storage.md#enable-lakehouse-storage).
+
+## Introduction
+
+When a table is created or altered with the option `'table.datalake.enabled' = 'true'`, Fluss will automatically create a corresponding Lance table with the same table path.
+The schema of the Paimon table matches that of the Fluss table.
+
+```sql title="Flink SQL"
+USE CATALOG fluss_catalog;
+
+CREATE TABLE fluss_order_with_lake (
+    `order_key` BIGINT,
+    `cust_key` INT NOT NULL,
+    `total_price` DECIMAL(15, 2),
+    `order_date` DATE,
+    `order_priority` STRING,
+    `clerk` STRING,
+    `ptime` AS PROCTIME(),
+    PRIMARY KEY (`order_key`) NOT ENFORCED
+ ) WITH (
+     'table.datalake.enabled' = 'true',
+     'table.datalake.freshness' = '30s'
+);
+```
+
+Then, the datalake tiering service continuously tiers data from Fluss to Lance. The parameter `table.datalake.freshness` controls the frequency that Fluss writes data to Paimon tables. By default, the data freshness is 3 minutes.  
+For primary key tables, changelogs are also generated in the Paimon format, enabling stream-based consumption via Paimon APIs.
+
+Since Fluss version 0.7, you can also specify Paimon table properties when creating a datalake-enabled Fluss table by using the `paimon.` prefix within the Fluss table properties clause.
+
+```sql title="Flink SQL"
+CREATE TABLE fluss_order_with_lake (
+    `order_key` BIGINT,
+    `cust_key` INT NOT NULL,
+    `total_price` DECIMAL(15, 2),
+    `order_date` DATE,
+    `order_priority` STRING,
+    `clerk` STRING,
+    `ptime` AS PROCTIME(),
+    PRIMARY KEY (`order_key`) NOT ENFORCED
+ ) WITH (
+     'table.datalake.enabled' = 'true',
+     'table.datalake.freshness' = '30s',
+     'paimon.file.format' = 'orc',
+     'paimon.deletion-vectors.enabled' = 'true'
+);
+```
+
+For example, you can specify the Paimon property `file.format` to change the file format of the Paimon table, or set `deletion-vectors.enabled` to enable or disable deletion vectors for the Paimon table.
+
+### Reading with other Engines
+
+Since the data tiered to Paimon from Fluss is stored as a standard Paimon table, you can use any engine that supports Paimon to read it. Below is an example using [StarRocks](https://paimon.apache.org/docs/master/engines/starrocks/):
+
+First, create a Paimon catalog in StarRocks:
+
+```sql title="StarRocks SQL"
+CREATE EXTERNAL CATALOG paimon_catalog
+PROPERTIES (
+       "type" = "paimon",
+       "paimon.catalog.type" = "filesystem",
+       "paimon.catalog.warehouse" = "/tmp/paimon_data_warehouse"
+);
+```
+
+> **NOTE**: The configuration values for `paimon.catalog.type` and `paimon.catalog.warehouse` must match those used when configuring Paimon as the lakehouse storage for Fluss in `server.yaml`.
+
+Then, you can query the `orders` table using StarRocks:
+
+```sql title="StarRocks SQL"
+-- The table is in the database `fluss`
+SELECT COUNT(*) FROM paimon_catalog.fluss.orders;
+```
+
+```sql title="StarRocks SQL"
+-- Query the system tables to view snapshots of the table
+SELECT * FROM paimon_catalog.fluss.enriched_orders$snapshots;
+```
+
+## Data Type Mapping
+
+When integrating with Paimon, Fluss automatically converts between Fluss data types and Paimon data types.  
+The following table shows the mapping between [Fluss data types](table-design/data-types.md) and Paimon data types:
+
+| Fluss Data Type               | Paimon Data Type              |
+|-------------------------------|-------------------------------|
+| BOOLEAN                       | BOOLEAN                       |
+| TINYINT                       | TINYINT                       |
+| SMALLINT                      | SMALLINT                      |
+| INT                           | INT                           |
+| BIGINT                        | BIGINT                        |
+| FLOAT                         | FLOAT                         |
+| DOUBLE                        | DOUBLE                        |
+| DECIMAL                       | DECIMAL                       |
+| STRING                        | STRING                        |
+| CHAR                          | CHAR                          |
+| DATE                          | DATE                          |
+| TIME                          | TIME                          |
+| TIMESTAMP                     | TIMESTAMP                     |
+| TIMESTAMP WITH LOCAL TIMEZONE | TIMESTAMP WITH LOCAL TIMEZONE |
+| BINARY                        | BINARY                        |
+| BYTES                         | BYTES                         |