You need to retrieve the table names by running the following query:
SELECT *
FROM information_schema.constraint_table_usage
WHERE table_name="your_table"
Alternatively you can use pg_constraint
to retrieve this information
select n.nspname as schema_name,
t.relname as table_name,
c.conname as constraint_name
from pg_constraint c
join pg_class t on c.conrelid = t.oid
join pg_namespace n on t.relnamespace = n.oid
where t.relname="your_table_name";
Then you can run the required ALTER TABLE statement:
ALTER TABLE your_table DROP CONSTRAINT constraint_name;
Of course you can make the query return the complete alter statement:
SELECT 'ALTER TABLE '||table_name||' DROP CONSTRAINT '||constraint_name||';'
FROM information_schema.constraint_table_usage
WHERE table_name in ('your_table', 'other_table')
Don’t forget to include the table_schema in the WHERE clause (and the ALTER statement) if there are multiple schemas with the same tables.