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Contents
# Copyright 2022 Google LLC
#
# Use of this source code is governed by an MIT-style
# license that can be found in the LICENSE file or at
# https://opensource.org/licenses/MIT.
class CreateTables < ActiveRecord::Migration[6.0]
def change
# Execute the entire migration as one DDL batch.
connection.ddl_batch do
create_table :singers, id: false do |t|
# Explicitly define the primary key with a custom name to prevent all primary key columns from being named `id`.
t.primary_key :singerid
t.string :first_name
t.string :last_name
end
create_table :albums, id: false do |t|
# Interleave the `albums` table in the parent table `singers`.
t.interleave_in :singers
t.primary_key :albumid
# `singerid` is defined as a `parent_key` which makes it a part of the primary key in the table definition, but
# it is not presented to ActiveRecord as part of the primary key, to prevent ActiveRecord from considering this
# to be an entity with a composite primary key (which is not supported by ActiveRecord).
t.parent_key :singerid
t.string :title
end
create_table :tracks, id: false do |t|
# Interleave the `tracks` table in the parent table `albums` and cascade delete all tracks that belong to an
# album when an album is deleted.
t.interleave_in :albums, :cascade
# `trackid` is considered the only primary key column by ActiveRecord.
t.primary_key :trackid
# `singerid` and `albumid` form the parent key of `tracks`. These are part of the primary key definition in the
# database, but are presented as parent keys to ActiveRecord.
t.parent_key :singerid
t.parent_key :albumid
t.string :title
t.numeric :duration
end
end
end
end
Version data entries
15 entries across 15 versions & 1 rubygems