Postgres list all constraints

list-constraints.sql

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 
    JOIN information_schema.key_column_usage AS kcu
      ON tc.constraint_name = kcu.constraint_name
    JOIN information_schema.constraint_column_usage AS ccu
      ON ccu.constraint_name = tc.constraint_name
WHERE constraint_type = 'FOREIGN KEY'

Nice ;)

good job

I ported this to ruby gem Sequel DSL if anyone is interested Note: I removed the WHERE constraint_type = 'FOREIGN KEY' clause, but it would be easy to add it in

def very_slow_constraint_lookup_for_table(table_name)
  DB[Sequel.as(:information_schema__table_constraints, :tc)].
    join(Sequel.as(:information_schema__key_column_usage, :kcu),
      :tc__constraint_name => :kcu__constraint_name
    ).
    join(Sequel.as(:information_schema__constraint_column_usage, :ccu),
      :tc__constraint_name => :ccu__constraint_name
    ).
    where(:tc__table_name => table_name.to_s).
    all
end

very_slow_constraint_lookup_for_table("my_table")

Example results:

[{:constraint_catalog=>"vydia",
  :constraint_schema=>"public",
  :constraint_name=>"asdfg",
  :table_catalog=>"vydia",
  :table_schema=>"public",
  :table_name=>"my_table",
  :constraint_type=>"FOREIGN KEY",
  :is_deferrable=>"NO",
  :initially_deferred=>"NO",
  :column_name=>"id",
  :ordinal_position=>1,
  :position_in_unique_constraint=>1},
{:constraint_catalog=>"vydia",
  :constraint_schema=>"public",
  :constraint_name=>"asdfg",
  :table_catalog=>"vydia",
  :table_schema=>"public",
  :table_name=>"my_table",
  :constraint_type=>"PRIMARY KEY",
  :is_deferrable=>"NO",
  :initially_deferred=>"NO",
  :column_name=>"id",
  :ordinal_position=>1,
  :position_in_unique_constraint=>nil}]

very helpful, thanks!

Very helpful! I used it to base this off: https://gist.github.com/wlievens/e875e489a398f856dc96a8b8dc88ec2c

very nice, thanks!

very helpful! thanks man

hi,
thnx for sharing the code,

In postgreSQL we can have same constraint name in different schema with the same table name or different. In that case we are getting some incorrect records.
by adding constraint schema name as qualifier we can avoid duplicate
tc.constraint_schema = kcu.constraint_schema ,
ccu.constraint_schema = tc.constraint_schema

Thank you very much for sharing.

nice :)

nice one.

Thanks a lot ^^

Holy crap! Was this gist so popular? I didn't realize 😆

nice