after mysql migration to postgres restarting primary key sequences and most importantly retaining older data for referential integrity aspect !

rename primary script.sql

--create new column to create sequences
alter table modnames add id serial; 
---update new column serial column with existing value
UPDATE modnames m
SET    id = m0.modnameid
FROM   modnames m0
where m.modnameid=m0.modnameid
---now tricky part is to tell new serial to start from max(existingid) for referential integrity
--scenarios
---to figure out your serial sequence 
SELECT adsrc FROM pg_attrdef WHERE adrelid = (SELECT oid FROM pg_class WHERE relname = 'table name goes here');
--and apply new set of serial sequences
Select setval('modnames_id_seq', (select max(modnameid)+1 from modname), false)
--test you applications
INSERT INTO public.modnames
(mname, modnameid, createdat, updatedat, recordstate)
VALUES('new entry set ', 0, now(), now(), 'active'::character varying);
--to find serial sequences
--delete old column and rename the older to new one 
ALTER TABLE modnames RENAME COLUMN id TO modnameid;