How do I list all schemas in PostgreSQL?

Question

When using PostgreSQL v9.1, how do I list all of the schemas using SQL?

I was expecting something along the lines of:

SELECT something FROM pg_blah;

Answer 1

To lists all schemas, use the (ANSI) standard INFORMATION_SCHEMA

select schema_name
from information_schema.schemata;

More details in the manual

alternatively:

select nspname
from pg_catalog.pg_namespace;

More details about pg_catalog in the manual

Answer 2

When using the psql command line, you may list all schema with command \dn.

Answer 3

Connect to the psql command --> psql --u {userName} {DBName} then you can type the below command to check how many schemas are present in the DB

DBName=# \dn

Else you can check the syntax by the below steps easily-

1. After connecting the the DB, press

   DBName=# help
   

You will get the below options:

You are using psql, the command-line interface to PostgreSQL.
Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit

Then press

DBName=# \?

You will get all the options very easily.

Answer 4

Beginning On postgres 9.3, One trick you can use in postgres to get the exact sql of informational command (such as \d, \du, \dp, etc) in psql is by using a transaction. Here's how the trick goes. Open one postgres session, then type your command :

begin;
\dn+

While the transaction still running, open another postgres session, and query the pg_stat_activity and you can get the exact sql.

postgres=# select query from pg_stat_activity ;
                                 query                                 
-----------------------------------------------------------------------
 SELECT n.nspname AS "Name",                                          +
   pg_catalog.pg_get_userbyid(n.nspowner) AS "Owner",                 +
   pg_catalog.array_to_string(n.nspacl, E'\n') AS "Access privileges",+
   pg_catalog.obj_description(n.oid, 'pg_namespace') AS "Description" +
 FROM pg_catalog.pg_namespace n                                       +
 WHERE n.nspname !~ '^pg_' AND n.nspname <> 'information_schema'      +
 ORDER BY 1;