DESCRIBE OUTPUT
Synopsis
DESCRIBE OUTPUT statement_name
DESCRIBE OUTPUT ( query )
Description
List the output columns of a prepared statement or a query, including the column name (or alias), catalog, schema, table, type, type size in bytes, and a boolean indicating if the column is aliased.
Examples
Prepare and describe a query with four output columns:
PREPARE my_select1 FROM
SELECT * FROM nation;
DESCRIBE OUTPUT my_select1;
Column Name | Catalog | Schema | Table | Type | Type Size | Aliased
-------------+---------+--------+--------+---------+-----------+---------
nationkey | tpch | sf1 | nation | bigint | 8 | false
name | tpch | sf1 | nation | varchar | 0 | false
regionkey | tpch | sf1 | nation | bigint | 8 | false
comment | tpch | sf1 | nation | varchar | 0 | false
(4 rows)
Prepare and describe a query whose output columns are expressions:
PREPARE my_select2 FROM
SELECT count(*) as my_count, 1+2 FROM nation;
DESCRIBE OUTPUT my_select2;
Column Name | Catalog | Schema | Table | Type | Type Size | Aliased
-------------+---------+--------+-------+--------+-----------+---------
my_count | | | | bigint | 8 | true
_col1 | | | | bigint | 8 | false
(2 rows)
Prepare and describe a row count query:
PREPARE my_create FROM
CREATE TABLE foo AS SELECT * FROM nation;
DESCRIBE OUTPUT my_create;
Column Name | Catalog | Schema | Table | Type | Type Size | Aliased
-------------+---------+--------+-------+--------+-----------+---------
rows | | | | bigint | 8 | false
(1 row)
You can also describe a query directly:
DESCRIBE OUTPUT (SELECT *, n_name AS "name" FROM nation);
Column Name | Catalog | Schema | Table | Type | Type Size | Aliased
-------------+---------+--------+--------+--------------+-----------+---------
n_nationkey | tpch | sf1 | nation | bigint | 8 | false
n_name | tpch | sf1 | nation | varchar(25) | 0 | false
n_regionkey | tpch | sf1 | nation | bigint | 8 | false
n_comment | tpch | sf1 | nation | varchar(152) | 0 | false
name | tpch | sf1 | nation | varchar(25) | 0 | true
(5 rows)