DESCRIBE TABLE
适用于: Databricks SQL Databricks Runtime
返回表的基本元数据信息。 元数据信息包括列名、列类型和列注释。 可根据需要指定分区规范或列名称,以分别返回与分区或列有关的元数据。 使用 Delta 表时,不会返回所有字段。
语法
{ DESC | DESCRIBE } [ TABLE ] [ EXTENDED | FORMATTED ] table_name { [ PARTITION clause ] | [ column_name ] }
参数
EXTENDED
或FORMATTED
如果指定了该参数,则显示有关指定列的详细信息,包括命令收集的列统计信息和其他元数据(例如架构限定符、所有者和访问时间)。
-
标识要描述的表。 该名称不得使用时态规范。 如果找不到表,Azure Databricks 会引发 TABLE_OR_VIEW_NOT_FOUND 错误。
-
一个可选参数,指示 Databricks SQL 为命名分区返回附加元数据。
-
一个可选参数,具有需说明的列名。 目前不允许指定嵌套列。
参数partition_spec
和column_name
互斥,不能同时指定。
示例
-- Creates a table `customer`. Assumes current schema is `salesdb`.
> CREATE TABLE customer(
cust_id INT,
state VARCHAR(20),
name STRING COMMENT 'Short name'
)
USING parquet
PARTITIONED BY (state);
> INSERT INTO customer PARTITION (state = 'AR') VALUES (100, 'Mike');
-- Returns basic metadata information for unqualified table `customer`
> DESCRIBE TABLE customer;
col_name data_type comment
----------------------- --------- ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
-- Returns basic metadata information for qualified table `customer`
> DESCRIBE TABLE salesdb.customer;
col_name data_type comment
----------------------- --------- ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
-- Returns additional metadata such as parent schema, owner, access time etc.
> DESCRIBE TABLE EXTENDED customer;
col_name data_type comment
---------------------------- ------------------------------ ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
# Detailed Table Information
Database default
Table customer
Owner <TABLE OWNER>
Created Time Tue Apr 07 22:56:34 JST 2020
Last Access UNKNOWN
Created By <SPARK VERSION>
Type MANAGED
Provider parquet
Location file:/tmp/salesdb.db/custom...
Serde Library org.apache.hadoop.hive.ql.i...
InputFormat org.apache.hadoop.hive.ql.i...
OutputFormat org.apache.hadoop.hive.ql.i...
Partition Provider Catalog
-- Returns partition metadata such as partitioning column name, column type and comment.
> DESCRIBE TABLE EXTENDED customer PARTITION (state = 'AR');
col_name data_type comment
------------------------------ ------------------------------ ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
# Detailed Partition Inform...
Database default
Table customer
Partition Values [state=AR]
Location file:/tmp/salesdb.db/custom...
Serde Library org.apache.hadoop.hive.ql.i...
InputFormat org.apache.hadoop.hive.ql.i...
OutputFormat org.apache.hadoop.hive.ql.i...
Storage Properties [serialization.format=1, pa...
Partition Parameters {transient_lastDdlTime=1586...
Created Time Tue Apr 07 23:05:43 JST 2020
Last Access UNKNOWN
Partition Statistics 659 bytes
# Storage Information
Location file:/tmp/salesdb.db/custom...
Serde Library org.apache.hadoop.hive.ql.i...
InputFormat org.apache.hadoop.hive.ql.i...
OutputFormat org.apache.hadoop.hive.ql.i...
------------------------------ ------------------------------ ----------
-- Returns the metadata for `name` column.
-- Optional `TABLE` clause is omitted and column is fully qualified.
> DESCRIBE customer salesdb.customer.name;
info_name info_value
--------- ----------
col_name name
data_type string
comment Short name
DESCRIBE DETAIL
DESCRIBE DETAIL [schema_name.]table_name
返回架构、分区、表大小等方面的信息。 例如,对于 Delta 表,你可以查看表的当前读取器和编写器版本。 请参阅使用 describe detail 查看 Delta Lake 表详细信息,了解详细信息架构。