til/postgres/show-the-hidden-queries-behind-backslash-commands.md

Show The Hidden Queries Behind Backslash Commands

The ECHO_HIDDEN variable in PostgreSQL's psql determines whether the queries behind backslash commands are displayed. It defaults to false. So, generally, when you run something like \d or \l+, you'll just see the result and not the query that helped produce it.

If you're curious what's behind any of these backslash commands, then set ECHO_HIDDEN to true to get a look.

> \set ECHO_HIDDEN true
> \d
********* QUERY **********
SELECT n.nspname as "Schema",
  c.relname as "Name",
  CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'm' THEN 'materialized view' WHEN 'i' THEN 'index' WHEN 'S' THEN 'sequence' WHEN 's' THEN 'special' WHEN 'f' THEN 'foreign table' WHEN 'p' THEN 'partitioned table' WHEN 'I' THEN 'partitioned index' END as "Type",
  pg_catalog.pg_get_userbyid(c.relowner) as "Owner"
FROM pg_catalog.pg_class c
     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE c.relkind IN ('r','p','v','m','S','f','')
      AND n.nspname <> 'pg_catalog'
      AND n.nspname <> 'information_schema'
      AND n.nspname !~ '^pg_toast'
  AND pg_catalog.pg_table_is_visible(c.oid)
ORDER BY 1,2;
**************************

               List of relations
 Schema |     Name     |   Type   |   Owner
--------+--------------+----------+------------
 public | users        | table    | jbranchaud
 public | users_id_seq | sequence | jbranchaud

That query is what psql uses to list the relations for your current database.