diff options
Diffstat (limited to 'doc/development/database/add_foreign_key_to_existing_column.md')
| -rw-r--r-- | doc/development/database/add_foreign_key_to_existing_column.md | 9 |
1 files changed, 3 insertions, 6 deletions
diff --git a/doc/development/database/add_foreign_key_to_existing_column.md b/doc/development/database/add_foreign_key_to_existing_column.md index a5d40d455d8..f83dc35b4a6 100644 --- a/doc/development/database/add_foreign_key_to_existing_column.md +++ b/doc/development/database/add_foreign_key_to_existing_column.md @@ -58,6 +58,9 @@ emails = Email.where(user_id: 1) # returns emails for the deleted user Add a `NOT VALID` foreign key constraint to the table, which enforces consistency on the record changes. +[Using the `with_lock_retries` helper method is advised when performing operations on high-traffic tables](../migration_style_guide.md#when-to-use-the-helper-method), +in this case, if the table or the foreign table is a high-traffic table, we should use the helper method. + In the example above, you'd be still able to update records in the `emails` table. However, when you'd try to update the `user_id` with non-existent value, the constraint causes a database error. Migration file for adding `NOT VALID` foreign key: @@ -66,8 +69,6 @@ Migration file for adding `NOT VALID` foreign key: class AddNotValidForeignKeyToEmailsUser < ActiveRecord::Migration[5.2] include Gitlab::Database::MigrationHelpers - DOWNTIME = false - def up # safe to use: it requires short lock on the table since we don't validate the foreign key add_foreign_key :emails, :users, on_delete: :cascade, validate: false @@ -94,8 +95,6 @@ Example for cleaning up records in the `emails` table within a database migratio class RemoveRecordsWithoutUserFromEmailsTable < ActiveRecord::Migration[5.2] include Gitlab::Database::MigrationHelpers - DOWNTIME = false - disable_ddl_transaction! class Email < ActiveRecord::Base @@ -130,8 +129,6 @@ Migration file for validating the foreign key: class ValidateForeignKeyOnEmailUsers < ActiveRecord::Migration[5.2] include Gitlab::Database::MigrationHelpers - DOWNTIME = false - def up validate_foreign_key :emails, :user_id end |