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# frozen_string_literal: true
class AddUniqueConstraintToApprovalsUserIdAndMergeRequestId < ActiveRecord::Migration[5.0]
include Gitlab::Database::MigrationHelpers
DOWNTIME = false
disable_ddl_transaction!
def up
remove_duplicates
add_concurrent_index :approvals, [:user_id, :merge_request_id], unique: true
end
def down
remove_concurrent_index :approvals, [:user_id, :merge_request_id]
end
private
def remove_duplicates
add_concurrent_index :approvals, [:user_id, :merge_request_id, :id]
execute <<-SQL
DELETE FROM approvals
USING (
SELECT user_id, merge_request_id, MIN(id) as min_id
FROM approvals
GROUP BY user_id, merge_request_id
HAVING COUNT(id) > 1
) as approvals_with_duplicates
WHERE approvals_with_duplicates.user_id = approvals.user_id
AND approvals_with_duplicates.merge_request_id = approvals.merge_request_id
AND approvals_with_duplicates.min_id <> approvals.id;
SQL
remove_concurrent_index :approvals, [:user_id, :merge_request_id, :id]
end
end
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