How to delete everything from all tables without dropping the database [duplicate] - ruby-on-rails

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Closed 10 years ago.
Possible Duplicate:
Truncating all tables in a postgres database
How can I delete all data from all tables without dropping the database?

Answer 1

You can use raw connection object to execute SQL statements:
connection = ActiveRecord::Base.connection
connection.tables.each{|t| connection.execute "TRUNCATE #{t}"}

Answer 2

Use the DatabaseCleaner gem.
DatabaseCleaner.strategy = :truncation
DatabaseCleaner.clean
If you absolutely must have this within a rake task, just wrap it up in one yourself.

Answer 3

For ad-hoc use
Run this statement in the database (Careful! Nukes all your data!):
DO
$func$
BEGIN
EXECUTE (
SELECT 'TRUNCATE TABLE '
|| string_agg(quote_ident(t.tablename), ', ')
|| ' CASCADE'
FROM pg_tables t
WHERE t.schemaname = 'public' -- assuming default schema
);
END
$func$;
The DO command was introduced with PostgreSQL 9.0. You would create a plpgsql function and execute it for older versions.
Compare to the closely related question: Truncating all tables in a Postgres database
For repeated use
It might be simpler (and faster!) to create a "template" database (let's name it my_template) with your vanilla structure and all empty tables. Then go through a DROP / CREATE DATABASE cycle:
DROP DATABASE mydb;
CREATE DATABASE mydb TEMPLATE my_template;
This is extremely fast, because PostgreSQL copies the whole structure on the file level. No concurrency issues or other overhead slowing you down.

Answer 4

You can do a backup of the database with pg_dump and restore only the schema of the database with pg_resotre --schema-only , it deletes all data in all tables.
Exemple:
To backup.
pg_dump --format=c --compress=0 -h localhost mydatabasename > mydump.dmp
To restore only schema information without data.
pg_restore -c --schema-only mydump.dmp | psql -h localhost mydatabasename