2026 年 6 月 30 日之后，Amazon Redshift 不再支持使用 Python UDF。我们将分阶段开始执行。有关 Python 生命周期终止和迁移选项详情的更多信息，请参阅 2025 年 6 月 30 日发布的[博客文章](https://www.amazonaws.cn/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/)。

# 使用 SHOW 命令
<a name="discovering-metadata-show-commands"></a>

如果驱动程序元数据 API 未涵盖您的使用案例，则可以使用 Amazon Redshift `SHOW` 命令来检索元数据。`SHOW` 命令经过优化，可快速检索元数据。当您在交互式 SQL 会话中需要元数据时，或者当您的应用程序通过不公开驱动程序元数据 API 的客户端进行连接时，它们很有用。

常见的发现操作支持以下 `SHOW` 命令：
+ [SHOW DATABASES](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_DATABASES.html)
+ [SHOW SCHEMAS](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_SCHEMAS.html)
+ [SHOW TABLES](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_TABLES.html)
+ [SHOW COLUMNS](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_COLUMNS.html)
+ [SHOW CONSTRAINTS](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_CONSTRAINTS.html)
+ [SHOW GRANTS](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_GRANTS.html)
+ [SHOW FUNCTIONS](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_FUNCTIONS.html)
+ [SHOW PROCEDURES](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_PROCEDURES.html)
+ [SHOW PARAMETERS](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW_PARAMETERS.html)

## 示例
<a name="r_SHOW_LIST-examples"></a>

```
SHOW SCHEMAS FROM DATABASE dev;

database_name |     schema_name      | schema_owner | schema_type |         schema_acl          | source_database | schema_option 
---------------+----------------------+--------------+-------------+-----------------------------+-----------------+---------------
dev           | pg_automv            |            1 | local       |                             |                 | 
dev           | pg_catalog           |            1 | local       | jpuser=UC/jpuser~=U/jpuser  |                 | 
dev           | public               |            1 | local       | jpuser=UC/jpuser~=UC/jpuser |                 | 
dev           | information_schema   |            1 | local       | jpuser=UC/jpuser~=U/jpuser  |                 | 
dev           | schemad79cd6d93bf043 |            1 | local       |                             |                 |
```

```
SHOW TABLES FROM SCHEMA dev.s1 LIKE '%view' LIMIT 1;

database_name | schema_name |    table_name     | table_type |              table_acl               | remarks | owner | last_altered_time | last_modified_time | dist_style |   table_subtype   
---------------+-------------+-------------------+------------+--------------------------------------+---------+-------+-------------------+--------------------+------------+-------------------
dev           | s1          | late_binding_view | VIEW       | {alice=arwdRxtDPA/alice,bob=d/alice} |         | alice |                   |                    |            | LATE BINDING VIEW
```

```
SHOW COLUMNS FROM TABLE second_db.public.t22;

 database_name | schema_name | table_name | column_name | ordinal_position | column_default | is_nullable |          data_type          | character_maximum_length | numeric_precision | numeric_scale | remarks | sort_key_type | sort_key | dist_key | encoding | collation 
---------------+-------------+------------+-------------+------------------+----------------+-------------+-----------------------------+--------------------------+-------------------+---------------+---------+---------------+----------+----------+----------+-----------
 second_db     | public      | t22        | col1        |                1 |                | YES         | integer                     |                          |                32 |             0 |         | INTERLEAVED   |       -1 |          | mostly8  | 
 second_db     | public      | t22        | col2        |                2 |                | YES         | character varying           |                      100 |                   |               |         | INTERLEAVED   |        2 |          | text255  | default
 second_db     | public      | t22        | col3        |                3 |                | YES         | timestamp without time zone |                          |                   |               |         |               |        0 |          | raw      | 
 second_db     | public      | t22        | col4        |                4 |                | YES         | numeric                     |                          |                10 |             2 |         |               |        0 |          | az64     |
```

有关更多信息，请参阅《Amazon Redshift 数据库开发人员指南》**中的 [SHOW](https://docs.amazonaws.cn/redshift/latest/dg/r_SHOW.html)。