Note: my answer is about really deleting the tables and other database objects; for deleting all data in the tables, i.e. truncating all tables, Endre Both has provided a similarily well-executed (direct execution) statement a month later.
For the cases where you can’t just DROP SCHEMA public CASCADE;, DROP OWNED BY current_user; or something, here’s a stand-alone SQL script I wrote, which is transaction-safe (i.e. you can put it between BEGIN; and either ROLLBACK; to just test it out or COMMIT; to actually do the deed) and cleans up “all” database objects… well, all those used in the database our application uses or I could sensibly add, which is:
- triggers on tables
- constraints on tables (FK, PK,
CHECK, UNIQUE)
- indicēs
VIEWs (normal or materialised)- tables
- sequences
- routines (aggregate functions, functions, procedures)
- all nōn-default (i.e. not
public or DB-internal) schemata “we” own: the script is useful when run as “not a database superuser”; a superuser can drop all schemata (the really important ones are still explicitly excluded, though)
- extensions (user-contributed but I normally deliberately leave them in)
Not dropped are (some deliberate; some only because I had no example in our DB):
- the
public schema (e.g. for extension-provided stuff in them)
- collations and other locale stuff
- event triggers
- text search stuff, … (see here for other stuff I might have missed)
- roles or other security settings
- composite types
- toast tables
- FDW and foreign tables
This is really useful for the cases when the dump you want to restore is of a different database schema version (e.g. with Debian dbconfig-common, Flyway or Liquibase/DB-Manul) than the database you want to restore it into.
I’ve also got a version which deletes “everything except two tables and what belongs to them” (a sequence, tested manually, sorry, I know, boring) in case someone is interested; the diff is small. Contact me or check this repo if interested.
SQL
-- Copyright © 2019, 2020
-- mirabilos <t.glaser@tarent.de>
--
-- Provided that these terms and disclaimer and all copyright notices
-- are retained or reproduced in an accompanying document, permission
-- is granted to deal in this work without restriction, including un‐
-- limited rights to use, publicly perform, distribute, sell, modify,
-- merge, give away, or sublicence.
--
-- This work is provided “AS IS” and WITHOUT WARRANTY of any kind, to
-- the utmost extent permitted by applicable law, neither express nor
-- implied; without malicious intent or gross negligence. In no event
-- may a licensor, author or contributor be held liable for indirect,
-- direct, other damage, loss, or other issues arising in any way out
-- of dealing in the work, even if advised of the possibility of such
-- damage or existence of a defect, except proven that it results out
-- of said person’s immediate fault when using the work as intended.
-- -
-- Drop everything from the PostgreSQL database.
DO $$
DECLARE
q TEXT;
r RECORD;
BEGIN
-- triggers
FOR r IN (SELECT pns.nspname, pc.relname, pt.tgname
FROM pg_catalog.pg_trigger pt, pg_catalog.pg_class pc, pg_catalog.pg_namespace pns
WHERE pns.oid=pc.relnamespace AND pc.oid=pt.tgrelid
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pt.tgisinternal=false
) LOOP
EXECUTE format('DROP TRIGGER %I ON %I.%I;',
r.tgname, r.nspname, r.relname);
END LOOP;
-- constraints #1: foreign key
FOR r IN (SELECT pns.nspname, pc.relname, pcon.conname
FROM pg_catalog.pg_constraint pcon, pg_catalog.pg_class pc, pg_catalog.pg_namespace pns
WHERE pns.oid=pc.relnamespace AND pc.oid=pcon.conrelid
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pcon.contype='f'
) LOOP
EXECUTE format('ALTER TABLE ONLY %I.%I DROP CONSTRAINT %I;',
r.nspname, r.relname, r.conname);
END LOOP;
-- constraints #2: the rest
FOR r IN (SELECT pns.nspname, pc.relname, pcon.conname
FROM pg_catalog.pg_constraint pcon, pg_catalog.pg_class pc, pg_catalog.pg_namespace pns
WHERE pns.oid=pc.relnamespace AND pc.oid=pcon.conrelid
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pcon.contype<>'f'
) LOOP
EXECUTE format('ALTER TABLE ONLY %I.%I DROP CONSTRAINT %I;',
r.nspname, r.relname, r.conname);
END LOOP;
-- indicēs
FOR r IN (SELECT pns.nspname, pc.relname
FROM pg_catalog.pg_class pc, pg_catalog.pg_namespace pns
WHERE pns.oid=pc.relnamespace
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pc.relkind='i'
) LOOP
EXECUTE format('DROP INDEX %I.%I;',
r.nspname, r.relname);
END LOOP;
-- normal and materialised views
FOR r IN (SELECT pns.nspname, pc.relname
FROM pg_catalog.pg_class pc, pg_catalog.pg_namespace pns
WHERE pns.oid=pc.relnamespace
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pc.relkind IN ('v', 'm')
) LOOP
EXECUTE format('DROP VIEW %I.%I;',
r.nspname, r.relname);
END LOOP;
-- tables
FOR r IN (SELECT pns.nspname, pc.relname
FROM pg_catalog.pg_class pc, pg_catalog.pg_namespace pns
WHERE pns.oid=pc.relnamespace
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pc.relkind='r'
) LOOP
EXECUTE format('DROP TABLE %I.%I;',
r.nspname, r.relname);
END LOOP;
-- sequences
FOR r IN (SELECT pns.nspname, pc.relname
FROM pg_catalog.pg_class pc, pg_catalog.pg_namespace pns
WHERE pns.oid=pc.relnamespace
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pc.relkind='S'
) LOOP
EXECUTE format('DROP SEQUENCE %I.%I;',
r.nspname, r.relname);
END LOOP;
-- extensions (only if necessary; keep them normally)
FOR r IN (SELECT pns.nspname, pe.extname
FROM pg_catalog.pg_extension pe, pg_catalog.pg_namespace pns
WHERE pns.oid=pe.extnamespace
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
) LOOP
EXECUTE format('DROP EXTENSION %I;', r.extname);
END LOOP;
-- aggregate functions first (because they depend on other functions)
FOR r IN (SELECT pns.nspname, pp.proname, pp.oid
FROM pg_catalog.pg_proc pp, pg_catalog.pg_namespace pns, pg_catalog.pg_aggregate pagg
WHERE pns.oid=pp.pronamespace
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast')
AND pagg.aggfnoid=pp.oid
) LOOP
EXECUTE format('DROP AGGREGATE %I.%I(%s);',
r.nspname, r.proname,
pg_get_function_identity_arguments(r.oid));
END LOOP;
-- routines (functions, aggregate functions, procedures, window functions)
IF EXISTS (SELECT * FROM pg_catalog.pg_attribute
WHERE attrelid='pg_catalog.pg_proc'::regclass
AND attname='prokind' -- PostgreSQL 11+
) THEN
q := 'CASE pp.prokind
WHEN ''p'' THEN ''PROCEDURE''
WHEN ''a'' THEN ''AGGREGATE''
ELSE ''FUNCTION''
END';
ELSIF EXISTS (SELECT * FROM pg_catalog.pg_attribute
WHERE attrelid='pg_catalog.pg_proc'::regclass
AND attname='proisagg' -- PostgreSQL ≤10
) THEN
q := 'CASE pp.proisagg
WHEN true THEN ''AGGREGATE''
ELSE ''FUNCTION''
END';
ELSE
q := '''FUNCTION''';
END IF;
FOR r IN EXECUTE 'SELECT pns.nspname, pp.proname, pp.oid, ' || q || ' AS pt
FROM pg_catalog.pg_proc pp, pg_catalog.pg_namespace pns
WHERE pns.oid=pp.pronamespace
AND pns.nspname NOT IN (''information_schema'', ''pg_catalog'', ''pg_toast'')
' LOOP
EXECUTE format('DROP %s %I.%I(%s);', r.pt,
r.nspname, r.proname,
pg_get_function_identity_arguments(r.oid));
END LOOP;
-- nōn-default schemata we own; assume to be run by a not-superuser
FOR r IN (SELECT pns.nspname
FROM pg_catalog.pg_namespace pns, pg_catalog.pg_roles pr
WHERE pr.oid=pns.nspowner
AND pns.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast', 'public')
AND pr.rolname=current_user
) LOOP
EXECUTE format('DROP SCHEMA %I;', r.nspname);
END LOOP;
-- voilà
RAISE NOTICE 'Database cleared!';
END; $$;
Tested, except later additions (extensions contributed by Clément Prévost), on PostgreSQL 9.6 (jessie-backports). Aggregate removal tested on 9.6 and 12.2, procedure removal tested on 12.2 as well. Bugfixes and further improvements welcome!
