mirror of
https://github.com/discourse/discourse.git
synced 2024-12-20 01:49:26 +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.
29 lines
855 B
Ruby
29 lines
855 B
Ruby
# frozen_string_literal: true
|
|
|
|
class CopyNotificationsIdValues < ActiveRecord::Migration[7.0]
|
|
disable_ddl_transaction!
|
|
|
|
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"
|
|
|
|
min_id, max_id = execute("SELECT MIN(id), MAX(id) FROM notifications")[0].values
|
|
batch_size = 10_000
|
|
|
|
(min_id..max_id).step(batch_size) { |start_id| execute <<~SQL } if min_id && max_id
|
|
UPDATE notifications
|
|
SET new_id = id
|
|
WHERE id >= #{start_id} AND id < #{start_id + batch_size} AND new_id != id
|
|
SQL
|
|
end
|
|
|
|
def down
|
|
raise ActiveRecord::IrreversibleMigration
|
|
end
|
|
end
|