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class FixAccountsUniqueIndex < ActiveRecord::Migration[5.2]
class Account < ApplicationRecord
# Dummy class, to make migration possible across version changes
has_one :user, inverse_of: :account
def local?
domain.nil?
end
def acct
local? ? username : "#{username}@#{domain}"
end
end
class StreamEntry < ApplicationRecord
# Dummy class, to make migration possible across version changes
belongs_to :account, inverse_of: :stream_entries
end
disable_ddl_transaction!
def up
say ''
say 'WARNING: This migration may take a *long* time for large instances'
say 'It will *not* lock tables for any significant time, but it may run'
say 'for a very long time. We will pause for 10 seconds to allow you to'
say 'interrupt this migration if you are not ready.'
say ''
say 'This migration will irreversibly delete user accounts with duplicate'
say 'usernames. You may use the `rake mastodon:maintenance:find_duplicate_usernames`'
say 'task to manually deal with such accounts before running this migration.'
10.downto(1) do |i|
say "Continuing in #{i} second#{i == 1 ? '' : 's'}...", true
sleep 1
end
duplicates = Account.connection.select_all('SELECT string_agg(id::text, \',\') AS ids FROM accounts GROUP BY lower(username), lower(domain) HAVING count(*) > 1').to_hash
duplicates.each do |row|
deduplicate_account!(row['ids'].split(','))
end
remove_index :accounts, name: 'index_accounts_on_username_and_domain_lower' if index_name_exists?(:accounts, 'index_accounts_on_username_and_domain_lower')
safety_assured { execute 'CREATE UNIQUE INDEX CONCURRENTLY index_accounts_on_username_and_domain_lower ON accounts (lower(username), lower(domain))' }
remove_index :accounts, name: 'index_accounts_on_username_and_domain' if index_name_exists?(:accounts, 'index_accounts_on_username_and_domain')
end
def down
raise ActiveRecord::IrreversibleMigration
end
private
def deduplicate_account!(account_ids)
accounts = Account.where(id: account_ids).to_a
accounts = accounts.first.local? ? accounts.sort_by(&:created_at) : accounts.sort_by(&:updated_at).reverse
reference_account = accounts.shift
say_with_time "Deduplicating @#{reference_account.acct} (#{accounts.size} duplicates)..." do
accounts.each do |other_account|
if other_account.public_key == reference_account.public_key
# The accounts definitely point to the same resource, so
# it's safe to re-attribute content and relationships
merge_accounts!(reference_account, other_account)
elsif other_account.local?
# Since domain is in the GROUP BY clause, both accounts
# are always either going to be local or not local, so only
# one check is needed. Since we cannot support two users with
# the same username locally, one has to go. 😢
other_account.user&.destroy
end
other_account.destroy
end
end
end
def merge_accounts!(main_account, duplicate_account)
[Status, Mention, StatusPin, StreamEntry].each do |klass|
klass.where(account_id: duplicate_account.id).in_batches.update_all(account_id: main_account.id)
end
# Since it's the same remote resource, the remote resource likely
# already believes we are following/blocking, so it's safe to
# re-attribute the relationships too. However, during the presence
# of the index bug users could have *also* followed the reference
# account already, therefore mass update will not work and we need
# to check for (and skip past) uniqueness errors
[Favourite, Follow, FollowRequest, Block, Mute].each do |klass|
klass.where(account_id: duplicate_account.id).find_each do |record|
begin
record.update_attribute(:account_id, main_account.id)
rescue ActiveRecord::RecordNotUnique
next
end
end
end
[Follow, FollowRequest, Block, Mute].each do |klass|
klass.where(target_account_id: duplicate_account.id).find_each do |record|
begin
record.update_attribute(:target_account_id, main_account.id)
rescue ActiveRecord::RecordNotUnique
next
end
end
end
end
end
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