How do I exclude data from local table schema_migrations from being pushed to Heroku DB?

Question

I was able to push my Ruby on Rails app with MySQL(local dev) to the Heroku server along with migrating my model with the command heroku rake db:migrate. I have also read the documentation on Database Import/Export. Is that doc referring to pushing actual data from my local dev DB to whichever Heroku's DB? Do I need to modify anything in the file database.yml to make it happen?

I ran the following command:

heroku db:push

and I am getting the error:

Sending data
2 tables, 3 records
!!! Caught Server    Exception                                   | ETA:  --:--:--
Taps Server Error: PGError ERROR:  duplicate key value violates unique constraint
"unique_schema_migrations"

I have 2 tables, one I create for my app and the other schema_migrations. The total number of entries among the 2 tables is 3. I'm also printing the number of entries I have in the table I have created and it's showing 0.

Any ideas what I might be missing or what I am doing wrong?

EDIT: I figured out the above, Heroku's DB already have schema_migrations the moment I ran migrate.

New question: Does anyone know how I can exclude data from a specific table from being pushed to Heroku DB. The table to exclude in this case will be schema_migrations.

Not so good solution: I googled around and someone else was having the same issue. He suggested naming the schema_migrations table to zschema_migrations. In this way data from the other tables will be pushed properly until it fails on the last table. It's a pretty bad solution but will do for the time being.

A better solution will be to use an existing Rails command which can reset a specific table from a database. I don't think Rake can do that.

Answer 1

This is kind of a guess based on the error you're getting, but push looks like it grabs the schema and the data. I'd try push to an empty database.

Answer 2

Two possible options:

1. The heroku gem and the taps gem (which it uses to synchronize databases) are both open-source - you could fork them, alter the taps client API to support excluding tables from a push, then alter the heroku gem to use that new option.

2. You could write a wrapper script that uses pgdump to backup the schema_migrations table, drops that table, heroku pushes the database, then reloads the table.

Answer 3

A feedback for New question: Does anyone know how I can exclude data from a specific table from being pushed to Heroku DB. The table to exclude in this case will be schema_migrations.

Would it be a problem to have a rake task like this:

and run it like: rake db:clean_tables RAILS_ENV=....

namespace :db do
  namespace :clean_tables do
    desc "cleanup a_table"
      ActiveRecord::Base.connection.execute("delete from a_table")
    end
  end
end

Answer 4

I've just deployed a Rails 3 beta app to heroku on their new bamboo server. I can now upload data from my local dev machine to the heroku database by doing:

heroku rake db:fixtures:load test/fixtures/my_model.yml

The data is then properly propagated in the Heroku database. Even though I specified a specific data file, it automatically pushes data from my other yaml files. It probably has something to do with my model relationships.

Answer 5

If your databases are out of sync you can always reset the Heroku database before pushing using

heroku db:reset

Answer 6

To push/pull from specific tables

heroku db:pull --tables logs,tags

http://blog.heroku.com/archives/2010/4/21/supporting_big_data_part_1