> For the complete documentation index, see [llms.txt](https://docs.starrocks.io/llms.txt). This page is also available as Markdown at its `.md` URL.

# REFRESH EXTERNAL TABLE

REFRESH EXTERNAL TABLE metadata cached in StarRocks. The metadata is from tables in data lakes. This statement is used in the following scenarios:

* **External table**: When using a Hive external table or Hudi external table to query data in Apache Hive™ or Apache Hudi, you can execute this statement to update the metadata of a Hive table or Hudi table cached in StarRocks.
* **External catalog**: When using an [external catalog](https://docs.starrocks.io/docs/data_source/catalog/catalog_overview.md) (except for JDBC Catalog) to query data in the corresponding data source, you can execute this statement to update the metadata cached in StarRocks.

> **NOTE**
>
> Only users with the ALTER privilege on the corresponding external table can perform this operation.

## Basic concepts[​](#basic-concepts "Direct link to Basic concepts")

* **Hive external table**: is created and stored in StarRocks. You can use it to query Hive data.
* **Hudi external table**: is created and stored in StarRocks. You can use it to query Hudi data.
* **Hive table**: is created and stored in Hive.
* **Hudi table**: is created and stored in Hudi.

## Syntaxes and parameters[​](#syntaxes-and-parameters "Direct link to Syntaxes and parameters")

The following describes the syntaxes and parameters based on different cases:

* External table

  ```sql
  REFRESH EXTERNAL TABLE table_name 
  [PARTITION ('partition_name', ...)]

  ```

  | **Parameter**   | **Required** | **Description**                                                                                                                                                                   |
  | --------------- | ------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
  | table_name     | Yes          | The name of a Hive external table or Hudi external table.                                                                                                                         |
  | partition_name | No           | The names of the partitions of a Hive table or Hudi table. Specifying this parameter updates the metadata of the partitions of the Hive table and Hudi table cached in StarRocks. |

* External catalog

  ```sql
  REFRESH EXTERNAL TABLE [external_catalog.][db_name.]table_name
  [PARTITION ('partition_name', ...)]

  ```

  | **Parameter**     | **Required** | **Description**                                                                                                                             |
  | ----------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------------- |
  | external_catalog | No           | The name of the external catalog, which supports Hive, Hudi, Delta Lake, and MaxCompute (since v3.3) catalogs.                              |
  | db_name          | No           | The name of the database where the destination table resides.                                                                               |
  | table_name       | Yes          | The name of the table.                                                                                                                      |
  | partition_name   | No           | The names of the partitions. Specifying this parameter updates the metadata of the partitions of the destination table cached in StarRocks. |

## Usage notes[​](#usage-notes "Direct link to Usage notes")

Only users who have the `ALTER_PRIV` privilege can execute this statement to update the metadata of Hive tables and Hudi tables cached in StarRocks.

## Examples[​](#examples "Direct link to Examples")

Usage examples in different cases are as follows:

### External table[​](#external-table "Direct link to External table")

Example 1: Update the cached metadata of the corresponding Hive table in StarRocks by specifying the external table `hive1`.

```sql
REFRESH EXTERNAL TABLE hive1;

```

Example 2: Update the cached metadata of the partitions of the corresponding Hudi table in StarRocks by specifying the external table `hudi1` and the partitions in that table.

```sql
REFRESH EXTERNAL TABLE hudi1
PARTITION ('date=2022-12-20', 'date=2022-12-21');

```

### External catalog[​](#external-catalog "Direct link to External catalog")

Example 1: Update the metadata of `hive_table` cached in StarRocks.

```sql
REFRESH EXTERNAL TABLE hive_catalog.hive_db.hive_table;

```

Or

```sql
USE hive_catalog.hive_db;
REFRESH EXTERNAL TABLE hive_table;

```

Example 2: Update the metadata of the second-level partition `p2` in `hive_table` cached in StarRocks.

```sql
USE hive_catalog.hive_db;
REFRESH EXTERNAL TABLE hive_table PARTITION ('p1=${date}/p2=${hour}');

```

Example 3: Update the metadata of the partitions of `hudi_table` cached in StarRocks.

```sql
REFRESH EXTERNAL TABLE hudi_catalog.hudi_db.hudi_table
PARTITION ('date=2022-12-20', 'date=2022-12-21');

```