从补丁 198 开始，Amazon Redshift 将不再支持创建新的 Python UDF。现有的 Python UDF 将继续正常运行至 2026 年 6 月 30 日。有关更多信息，请参阅[博客文章](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/)。

# SHOW EXTERNAL TABLE
<a name="r_SHOW_EXTERNAL_TABLE"></a>

显示外部表的定义，包括表属性和列属性。您可以使用 SHOW EXTERNAL TABLE 语句的输出来重新创建表。

有关外部表创建的更多信息，请参阅[CREATE EXTERNAL TABLE](r_CREATE_EXTERNAL_TABLE.md)。

## 语法
<a name="r_SHOW_EXTERNAL_TABLE-synopsis"></a>

```
SHOW EXTERNAL TABLE [external_database].external_schema.table_name [ PARTITION ]
```

## 参数
<a name="r_SHOW_EXTERNAL_TABLE-parameters"></a>

 *external\$1database*   
关联的外部数据库的名称。此参数为可选的。

 *external\$1schema*   
关联的外部 schema 的名称。

 *table\$1name*   
要显示的表的名称。

PARTITION   
显示 ALTER TABLE 语句以将分区添加到表定义。

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

以下示例基于定义如下的外部表：

```
CREATE EXTERNAL TABLE my_schema.alldatatypes_parquet_test_partitioned (
     csmallint smallint,
     cint int,
     cbigint bigint,
     cfloat float4,
     cdouble float8,
     cchar char(10),
     cvarchar varchar(255),
     cdecimal_small decimal(18,9),
     cdecimal_big decimal(30,15),
     ctimestamp TIMESTAMP,
     cboolean boolean,
     cstring varchar(16383)
)
PARTITIONED BY (cdate date, ctime TIMESTAMP)
STORED AS PARQUET
LOCATION 's3://amzn-s3-demo-bucket/alldatatypes_parquet_partitioned';
```

以下是 SHOW EXTERNAL TABLE 命令和表 `my_schema.alldatatypes_parquet_test_partitioned` 的输出示例。

```
SHOW EXTERNAL TABLE my_schema.alldatatypes_parquet_test_partitioned;
```

```
"CREATE EXTERNAL TABLE my_schema.alldatatypes_parquet_test_partitioned (
    csmallint smallint,
    cint int,
    cbigint bigint,
    cfloat float4,
    cdouble float8,
    cchar char(10),
    cvarchar varchar(255),
    cdecimal_small decimal(18,9),
    cdecimal_big decimal(30,15),
    ctimestamp timestamp,
    cboolean boolean,
    cstring varchar(16383)
)
PARTITIONED BY (cdate date, ctime timestamp)
ROW FORMAT SERDE 'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
STORED AS INPUTFORMAT 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'
OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION 's3://amzn-s3-demo-bucket/alldatatypes_parquet_partitioned';"
```

以下是同一个表的 SHOW EXTERNAL TABLE 命令和输出的示例，但参数中也指定了数据库。

```
SHOW EXTERNAL TABLE my_database.my_schema.alldatatypes_parquet_test_partitioned;
```

```
"CREATE EXTERNAL TABLE my_database.my_schema.alldatatypes_parquet_test_partitioned (
    csmallint smallint,
    cint int,
    cbigint bigint,
    cfloat float4,
    cdouble float8,
    cchar char(10),
    cvarchar varchar(255),
    cdecimal_small decimal(18,9),
    cdecimal_big decimal(30,15),
    ctimestamp timestamp,
    cboolean boolean,
    cstring varchar(16383)
)
PARTITIONED BY (cdate date, ctime timestamp)
ROW FORMAT SERDE 'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
STORED AS INPUTFORMAT 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'
OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION 's3://amzn-s3-demo-bucket/alldatatypes_parquet_partitioned';"
```

以下是使用 `PARTITION` 参数时的 SHOW EXTERNAL TABLE 命令和输出的示例。输出包含 ALTER TABLE 语句，可用于将分区添加到表定义。

```
SHOW EXTERNAL TABLE my_schema.alldatatypes_parquet_test_partitioned PARTITION;
```

```
"CREATE EXTERNAL TABLE my_schema.alldatatypes_parquet_test_partitioned (
    csmallint smallint,
    cint int,
    cbigint bigint,
    cfloat float4,
    cdouble float8,
    cchar char(10),
    cvarchar varchar(255),
    cdecimal_small decimal(18,9),
    cdecimal_big decimal(30,15),
    ctimestamp timestamp,
    cboolean boolean,
    cstring varchar(16383)
)
PARTITIONED BY (cdate date)
ROW FORMAT SERDE 'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
STORED AS INPUTFORMAT 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'
OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION 's3://amzn-s3-demo-bucket/alldatatypes_parquet_partitioned';
ALTER TABLE my_schema.alldatatypes_parquet_test_partitioned ADD IF NOT EXISTS PARTITION (cdate='2021-01-01') LOCATION 's3://amzn-s3-demo-bucket/alldatatypes_parquet_partitioned2/cdate=2021-01-01';
ALTER TABLE my_schema.alldatatypes_parquet_test_partitioned ADD IF NOT EXISTS PARTITION (cdate='2021-01-02') LOCATION 's3://amzn-s3-demo-bucket/alldatatypes_parquet_partitioned2/cdate=2021-01-02';"
```