PG sql duplicate key value violates unique constraint "schema_migrations_pkey" code example

Example 1: duplicate key value violates unique constraint "pg_type_typname_nsp_index"

I was reading this. It seems this error rises when you are creating/updating the same table with parallel processing. I understand it depends because of this (as explained on the google group discussion).

So I think it depend from PostgreSQL itself and not from the connection driver or the module used for the multiprocessing.

Well, Actually, the only way I found to solve this is to create chunks big enough to have back a writing process slower than the calculation itself. With bigger chunks this error doesn't rise.

Example 2: duplicate key value violates unique constraint "django_migrations_pkey"

from django.db import connections

query = "SELECT setval('django_migrations_id_seq', (SELECT MAX(id) FROM django_migrations))"
cursor = connections['default'].cursor()
cursor.execute(query) 
row = cursor.fetchone()