DESC

Description

You can use the statement to perform the following operations:

• View the schema of a table stored in your StarRocks cluster, along with the type of the sort key and materialized view of the table.
• View the schema of a table stored in the following external data sources, such as Apache Hive™. Note that you can perform this operation only in StarRocks 2.4 and later versions.

Syntax

DESC[RIBE] { [[<catalog_name>.]<db_name>.]<table_name> [ALL] | FILES(files_loading_properties) }

Parameters

Parameter	Required	Description
catalog_name	No	The name of the internal catalog or an external catalog. If you set the value of the parameter to the name of the internal catalog, which is default_catalog, you can view the schema of the table stored in your StarRocks cluster. If you set the value of the parameter to the name of an external catalog, you can view the schema of the table stored in the external data source.
db_name	No	The database name.
table_name	Yes	The table name.
ALL	No	If this keyword is specified, you can view the type of the sort key, materialized view, and schema of a table stored in your StarRocks cluster. If this keyword is not specified, you only view the table schema. Do not specify this keyword when you view the schema of a table stored in an external data source.
FILES	No	The FILES() table function. From v3.3.4 onwards, you can use DESC with FILES() to view the schema information of files stored in remote storage. For detailed information, see Function reference - FILES().

Output

+-----------+---------------+-------+------+------+-----+---------+-------+
| IndexName | IndexKeysType | Field | Type | Null | Key | Default | Extra |
+-----------+---------------+-------+------+------+-----+---------+-------+

The following table describes the parameters returned by this statement.

Parameter	Description
IndexName	The table name. If you view the schema of a table stored in an external data source, this parameter is not returned.
IndexKeysType	The type of the sort key of the table. If you view the schema of a table stored in an external data source, this parameter is not returned.
Field	The column name.
Type	The data type of the column.
Null	Whether the column values can be NULL. yes: indicates the values can be NULL. no: indicates the values cannot be NULL.
Key	Whether the column is used as the sort key. true: indicates the column is used as the sort key. false: indicates the column is not used as the sort key.
Default	The default value for the data type of the column. If the data type does not have a default value, a NULL is returned.
Extra	If you see the schema of a table stored in your StarRocks cluster, this field displays the following information about the column: The aggregate function used by the column, such as SUM and MIN. Whether a bloom filter index is created on the column. If so, the value of Extra is BLOOM_FILTER. If you see the schema of a table stored in external data sources, this field displays whether the column is the partition column. If the column is the partition column, the value of Extra is partition key.

Note: For information about how a materialized view is displayed in the output, see Example 2.

Examples

Example 1: View the schema of example_table stored in your StarRocks cluster.

DESC example_table;

Or

DESC default_catalog.example_db.example_table;

The output of the preceding statements is as follows.

+-------+---------------+------+-------+---------+-------+
| Field | Type          | Null | Key   | Default | Extra |
+-------+---------------+------+-------+---------+-------+
| k1    | TINYINT       | Yes  | true  | NULL    |       |
| k2    | DECIMAL(10,2) | Yes  | true  | 10.5    |       |
| k3    | CHAR(10)      | Yes  | false | NULL    |       |
| v1    | INT           | Yes  | false | NULL    |       |
+-------+---------------+------+-------+---------+-------+

Example 2: View the schema, type of the sort key, and materialized view of sales_records stored in your StarRocks cluster. In the following example, one materialized view store_amt is created based on sales_records.

DESC db1.sales_records ALL;

+---------------+---------------+-----------+--------+------+-------+---------+-------+
| IndexName     | IndexKeysType | Field     | Type   | Null | Key   | Default | Extra |
+---------------+---------------+-----------+--------+------+-------+---------+-------+
| sales_records | DUP_KEYS      | record_id | INT    | Yes  | true  | NULL    |       |
|               |               | seller_id | INT    | Yes  | true  | NULL    |       |
|               |               | store_id  | INT    | Yes  | true  | NULL    |       |
|               |               | sale_date | DATE   | Yes  | false | NULL    | NONE  |
|               |               | sale_amt  | BIGINT | Yes  | false | NULL    | NONE  |
|               |               |           |        |      |       |         |       |
| store_amt     | AGG_KEYS      | store_id  | INT    | Yes  | true  | NULL    |       |
|               |               | sale_amt  | BIGINT | Yes  | false | NULL    | SUM   |
+---------------+---------------+-----------+--------+------+-------+---------+-------+

Example 3: View the schema of hive_table stored in your Hive cluster.

DESC hive_catalog.hive_db.hive_table;

+-------+----------------+------+-------+---------+---------------+ 
| Field | Type           | Null | Key   | Default | Extra         | 
+-------+----------------+------+-------+---------+---------------+ 
| id    | INT            | Yes  | false | NULL    |               | 
| name  | VARCHAR(65533) | Yes  | false | NULL    |               | 
| date  | DATE           | Yes  | false | NULL    | partition key | 
+-------+----------------+------+-------+---------+---------------+

Example 4: View the schema of parquet file lineorder stored in AWS S3.

NOTE

For files stored in remote storage, DESC only returns three fields: Field, Type, and Null.

DESC FILES(
    "path" = "s3://inserttest/lineorder.parquet",
    "format" = "parquet",
    "aws.s3.access_key" = "AAAAAAAAAAAAAAAAAAAA",
    "aws.s3.secret_key" = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB",
    "aws.s3.region" = "us-west-2"
);

+------------------+------------------+------+
| Field            | Type             | Null |
+------------------+------------------+------+
| lo_orderkey      | int              | YES  |
| lo_linenumber    | int              | YES  |
| lo_custkey       | int              | YES  |
| lo_partkey       | int              | YES  |
| lo_suppkey       | int              | YES  |
| lo_orderdate     | int              | YES  |
| lo_orderpriority | varchar(1048576) | YES  |
| lo_shippriority  | int              | YES  |
| lo_quantity      | int              | YES  |
| lo_extendedprice | int              | YES  |
| lo_ordtotalprice | int              | YES  |
| lo_discount      | int              | YES  |
| lo_revenue       | int              | YES  |
| lo_supplycost    | int              | YES  |
| lo_tax           | int              | YES  |
| lo_commitdate    | int              | YES  |
| lo_shipmode      | varchar(1048576) | YES  |
+------------------+------------------+------+
17 rows in set (0.05 sec)

References

• CREATE DATABASE
• SHOW CREATE DATABASE
• USE
• SHOW DATABASES
• DROP DATABASE