mastodon/db/migrate/20231018193659_add_index_to_identities_uid_provider.rb

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# frozen_string_literal: true
class AddIndexToIdentitiesUidProvider < ActiveRecord::Migration[7.0]
disable_ddl_transaction!
def up
add_index_to_table
rescue ActiveRecord::RecordNotUnique
remove_duplicates_and_reindex
end
def down
remove_index_from_table
end
private
def remove_duplicates_and_reindex
deduplicate_records
reindex_records
rescue ActiveRecord::RecordNotUnique
retry
end
def reindex_records
remove_index_from_table
add_index_to_table
end
def add_index_to_table
add_index :identities, [:uid, :provider], unique: true, algorithm: :concurrently
end
def remove_index_from_table
remove_index :identities, [:uid, :provider]
end
def deduplicate_records
safety_assured do
execute <<~SQL.squish
DELETE FROM identities
WHERE id NOT IN (
SELECT DISTINCT ON(uid, provider) id FROM identities
ORDER BY uid, provider, id ASC
)
SQL
end
end
end