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Explain how to connect a external table. #7246

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11 changes: 11 additions & 0 deletions docs/flink-configuration.md
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,17 @@ The following properties can be set if using the REST catalog:
| token | | | A token which will be used to interact with the server. |


## exteral table configuration

Connect external tables in Flink, We can use the catalog configuration described above and the external table configuration described below.
The following properties can be set if using the external table:

| Property | Required | Values | Description |
| -----------------|----------| ------ |--------------------------------------------------------------------------------------------------------------------|
| catalog-name | | | User-specified catalog name. It's required because the connector don't have any default value. |
| catalog-database | | | The iceberg database name in the backend catalog, use the current flink database named by default |
| catalog-table | | | The iceberg table name in the backend catalog. Default to use the table name in the flink `CREATE TABLE` sentence. |

## Runtime configuration

### Read options
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148 changes: 0 additions & 148 deletions docs/flink-connector.md
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33 changes: 29 additions & 4 deletions docs/flink-ddl.md
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Expand Up @@ -153,7 +153,7 @@ CREATE TABLE `hive_catalog`.`default`.`sample` (
);
```

Table create commands support the commonly used [Flink create clauses](https://nightlies.apache.org/flink/flink-docs-master/docs/dev/table/sql/create/) including:
Table create commands support the commonly used [Flink create clauses](https://nightlies.apache.org/flink/flink-docs-stable/docs/dev/table/sql/create/) including:

* `PARTITION BY (column1, column2, ...)` to configure partitioning, Flink does not yet support hidden partitioning.
* `COMMENT 'table document'` to set a table description.
Expand Down Expand Up @@ -187,15 +187,40 @@ CREATE TABLE `hive_catalog`.`default`.`sample` (
CREATE TABLE `hive_catalog`.`default`.`sample_like` LIKE `hive_catalog`.`default`.`sample`;
```

For more details, refer to the [Flink `CREATE TABLE` documentation](https://nightlies.apache.org/flink/flink-docs-release-1.16/docs/dev/table/sql/create/).
For more details, refer to the [Flink `CREATE TABLE` documentation](https://nightlies.apache.org/flink/flink-docs-stable/docs/dev/table/sql/create/).

### `CONNECT TO A EXTERNAL TABLE`

Apache Flink provides access to externally stored iceberg tables that can be used as source or sink. It doesn't hold any data there, so the schema definition only declares how to map columns from an external iceberg table to Flink’s representation. Want to know how to connect to other common external systems, go to the [Flink official document](https://nightlies.apache.org/flink/flink-docs-stable/docs/connectors/table/overview/).

Flink SQL `CREATE TABLE sample_second (..) WITH ('connector'='iceberg', ...)` will access external iceberg table directly. The externally located database is automatically created if it does not exist when writing a record to a Flink table.

Flink iceberg connector provides table properties.
For more details, refer to the [exteral table configuration document](https://iceberg.apache.org/docs/latest/flink-configuration/#exteral-table-configuration)

Want to link database and table with different name like `hive_db.hive_iceberg_table`, we can connect table like this:

```sql
CREATE TABLE `default`. `sample_second` (
id BIGINT COMMENT 'unique id',
data STRING
) WITH (
'connector'='iceberg',
'catalog-type'='hive',
'uri'='thrift://localhost:9083',
'warehouse'='file:///path/to/warehouse'
'catalog-name'='hive_prod',
'catalog-database'='hive_db',
'catalog-table'='hive_iceberg_table',
);
```

### `ALTER TABLE`

Iceberg only support altering table properties:

```sql
ALTER TABLE `hive_catalog`.`default`.`sample` SET ('write.format.default'='avro')
ALTER TABLE `hive_catalog`.`default`.`sample` SET ('write.format.default'='avro');
```

### `ALTER TABLE .. RENAME TO`
Expand All @@ -210,4 +235,4 @@ To delete a table, run:

```sql
DROP TABLE `hive_catalog`.`default`.`sample`;
```
```