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How to sort the output of meta / slash commands in `psql`?

+3
−0

For example, how to sort the output below by the values in "Column" in the psql shell itself?

my_db=> \d auth_user
                                        Table "public.auth_user"
    Column    |           Type           | Collation | Nullable |                Default                
--------------+--------------------------+-----------+----------+---------------------------------------
 id           | integer                  |           | not null | nextval('auth_user_id_seq'::regclass)
 is_superuser | boolean                  |           | not null | 
 username     | character varying(150)   |           | not null | 
 first_name   | character varying(150)   |           |          | 
 last_name    | character varying(150)   |           | not null | 
 email        | character varying(254)   |           |          | 
 is_staff     | boolean                  |           | not null | false
 is_active    | boolean                  |           | not null | false
 password     | character varying(128)   |           |          | 
 last_login   | timestamp with time zone |           |          | 
 date_joined  | timestamp with time zone |           |          | 
Indexes:
    "auth_user_pkey" PRIMARY KEY, btree (id)
    "auth_user_username_6821ab7c_like" btree (username varchar_pattern_ops)
    "auth_user_username_key" UNIQUE CONSTRAINT, btree (username)

I know that this would be easy to do outside the psql shell, for example in Bash,

$ psql -U postgres -h localhost -d my_db -c '\d auth_user' | grep '^.*|' | sort -t'|' -k1

    Column    |           Type           | Collation | Nullable |                Default                
 date_joined  | timestamp with time zone |           |          | 
 email        | character varying(254)   |           |          | 
 first_name   | character varying(150)   |           |          | 
 id           | integer                  |           | not null | nextval('auth_user_id_seq'::regclass)
 is_active    | boolean                  |           | not null | false
 is_staff     | boolean                  |           | not null | false
 is_superuser | boolean                  |           | not null | 
 last_login   | timestamp with time zone |           |          | 
 last_name    | character varying(150)   |           | not null | 
 password     | character varying(128)   |           |          | 
 username     | character varying(150)   |           | not null | 

but I'm curious if this could be done in psql at all.

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1 answer

+3
−0

It's been a while, but the answer is "yes and no," I believe.

No: The describe-schema command doesn't (last I heard) allow any modification.

Yes: The describe-schema command also doesn't do anything that a SELECT statement from information_schema doesn't do, so something like this should work.

SELECT
  column_name
FROM
  information_schema.columns 
WHERE
  table_schema = 'public' 
AND
  table_name = 'auth_user' 
ORDER BY
  column_name ASC;

Assuming that they the PostgreSQL team hasn't moved anything in the years that I've had to deal with everything else, that should at least get you close.


Another approach to get around the immutability of the psql meta-commands is to list the SQL queries that are executed by them, and modify the relevant parts (e.g., by adding an ORDER BY clause).

For example, here's how to list the queries behind \d:

$ psql -E -d my_db
my_db=> \d auth_user

or

my_db=> \set ECHO_HIDDEN on
my_db=> \d auth_user

That will also show you the metadata query. Copy and paste that query and add your own ORDER BY clause.

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Works for me (1 comment)

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