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# See http://doc.gitlab.com/ce/development/migration_style_guide.html
# for more information on how to write migrations for GitLab.
class IssuesMovedToIdForeignKey < ActiveRecord::Migration
include Gitlab::Database::MigrationHelpers
# Set this constant to true if this migration requires downtime.
DOWNTIME = false
disable_ddl_transaction!
class Issue < ActiveRecord::Base
include EachBatch
self.table_name = 'issues'
def self.with_orphaned_moved_to_issues
if Gitlab::Database.postgresql?
# Be careful to use a second table here for comparison otherwise we'll null
# out all rows that don't have id == moved.to_id!
where('NOT EXISTS (SELECT true FROM issues B WHERE issues.moved_to_id = B.id)')
.where('moved_to_id IS NOT NULL')
else
# MySQL doesn't allow modification of the same table in a subquery,
# and using a temporary table isn't automatically guaranteed to work
# due to the MySQL query optimizer. See
# https://dev.mysql.com/doc/refman/5.7/en/update.html for more
# details.
joins('LEFT JOIN issues AS b ON issues.moved_to_id = b.id')
.where('issues.moved_to_id IS NOT NULL AND b.id IS NULL')
end
end
end
def up
Issue.with_orphaned_moved_to_issues.each_batch(of: 100) do |batch|
batch.update_all(moved_to_id: nil)
end
add_concurrent_foreign_key(
:issues,
:issues,
column: :moved_to_id,
on_delete: :nullify
)
# We're using a partial index here so we only index the data we actually
# care about.
add_concurrent_index(:issues, :moved_to_id, where: 'moved_to_id IS NOT NULL')
end
def down
remove_foreign_key_without_error(:issues, column: :moved_to_id)
remove_concurrent_index(:issues, :moved_to_id)
end
end
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