mirror of
https://github.com/discourse/discourse.git
synced 2024-12-11 17:15:47 +08:00
799a45a291
The `notifications.id` column is the most probable column to run out of values. This is because it is an `int` column that has only 2147483647 values and many notifications are generated on a regular basis in an active community. This commit migrates the column to `bigint`. These migrations do not use `ALTER TABLE ... COLUMN ... TYPE` in order to avoid the `ACCESS EXCLUSIVE` lock on the entire table. Instead, they create a new `bigint` column, copy the values to the new column and then sets the new column as primary key. Related columns (see `user_badges`, `shelved_notifications`) will be migrated in a follow-up commit.
39 lines
1.0 KiB
Ruby
39 lines
1.0 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
class AddBigIntNotificationsId < ActiveRecord::Migration[7.0]
|
|
def up
|
|
# Short-circuit if the table has been migrated already
|
|
result =
|
|
execute(
|
|
"SELECT data_type FROM information_schema.columns WHERE table_name = 'notifications' AND column_name = 'id' LIMIT 1",
|
|
)
|
|
data_type = result[0]["data_type"]
|
|
return if data_type.downcase == "bigint"
|
|
|
|
# Create new column
|
|
execute "ALTER TABLE notifications ADD COLUMN new_id BIGINT NOT NULL DEFAULT 0"
|
|
|
|
# Mirror new `id` values to `new_id`
|
|
execute <<~SQL.squish
|
|
CREATE FUNCTION mirror_notifications_id()
|
|
RETURNS trigger AS
|
|
$$
|
|
BEGIN
|
|
NEW.new_id = NEW.id;
|
|
RETURN NEW;
|
|
END;
|
|
$$
|
|
LANGUAGE plpgsql
|
|
SQL
|
|
|
|
execute <<~SQL.squish
|
|
CREATE TRIGGER notifications_new_id_trigger BEFORE INSERT ON notifications
|
|
FOR EACH ROW EXECUTE PROCEDURE mirror_notifications_id()
|
|
SQL
|
|
end
|
|
|
|
def down
|
|
raise ActiveRecord::IrreversibleMigration
|
|
end
|
|
end
|