Resetting Primary Key Sequence in Rails

README.md

I exported a table worth of data from one postgres instance as CSV and then directly imported into another postgres instance bypassing rails using the \copy command like so:

\copy my_table to ‘my_table.csv’ csv;

and

\copy my_table from ‘my_table.csv’ with (format csv);

Then I noticed that Rails was unable to create new records for that table:

MyModel.create(name: “Foo”)
ActiveRecord::RecordNotUnique: PG::UniqueViolation: ERROR:  duplicate key value violates unique constraint “my_models_pkey"

I could see quite clearly it was trying to insert with an id of “1”. The solution is to reset the primary key sequence like this:

ActiveRecord::Base.connection.reset_pk_sequence!(‘my_table’)