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Detect all duplicate foreign keys from public schema and generates a script that drops all duplicates but first.
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-- | |
-- Detect all duplicate foreign keys from public schema and generates a script that drops all duplicates but first. | |
-- | |
with fkeys as ( | |
select | |
tc.constraint_name, | |
tc.table_name, | |
kcu.column_name, | |
ccu.table_name as foreign_table_name, | |
ccu.column_name as foreign_column_name | |
from | |
information_schema.table_constraints as tc | |
inner join information_schema.key_column_usage as kcu | |
on tc.constraint_name = kcu.constraint_name and tc.table_schema = kcu.table_schema | |
inner join information_schema.constraint_column_usage as ccu | |
on ccu.constraint_name = tc.constraint_name and ccu.table_schema = tc.table_schema | |
where | |
tc.constraint_type = 'FOREIGN KEY' | |
and tc.table_schema = 'public' | |
), dups as ( | |
select | |
count(*), table_name, column_name, foreign_table_name, foreign_column_name | |
from fkeys | |
group by | |
table_name, column_name, foreign_table_name, foreign_column_name | |
having count(*) > 1 | |
), final as ( | |
select | |
row_number() over(partition by a.table_name, a.column_name, a.foreign_table_name, a.foreign_column_name) as num, | |
a.constraint_name, | |
a.table_name | |
from | |
fkeys a | |
inner join dups b | |
on a.table_name = b.table_name | |
and a.column_name = b.column_name | |
and a.foreign_table_name = b.foreign_table_name | |
and a.foreign_column_name = b.foreign_column_name | |
) | |
select | |
string_agg( | |
'alter table ' | |
|| 'public."' | |
|| table_name | |
|| '" drop constraint "' | |
|| constraint_name | |
|| '";', | |
chr(10) | |
) | |
from final | |
where num > 1; | |
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