Drop constraint quota_definitions_name_key (#3952)

* Drop constraint quota_definitions_name_key

On the name column in quota_defintions there were two unique
constraints/indexes. One unique index with name qd_name_index, which is
similar in postgres and mysql, and then an unique constraint on column
name with name in postgres=quota_definitions_name_key and name in
mysql=name.
Since the unique index already exists, we don't need the unique
constraint. Dropping it with this migration.

* Adjust migration to support mysql 5.7

---------

Co-authored-by: Sven Krieger <[email protected]>

Author: kathap

db/migrations/20240808118000_drop_unique_constraint_quota_definitions_name_key.rb

@@ -0,0 +1,37 @@
+Sequel.migration do
+  up do
+    if database_type == :mysql
+      if indexes(:quota_definitions).include?(:name)
+        alter_table :quota_definitions do
+          # rubocop:disable Sequel/ConcurrentIndex
+          drop_index :name, name: :name
+          # rubocop:enable Sequel/ConcurrentIndex
+        end
+      end
+    elsif database_type == :postgres
+      if indexes(:quota_definitions).include?(:quota_definitions_name_key)
+        alter_table :quota_definitions do
+          drop_constraint :quota_definitions_name_key
+        end
+      end
+    end
+  end
+
+  down do
+    if database_type == :mysql
+      unless indexes(:quota_definitions).include?(:name)
+        alter_table :quota_definitions do
+          # rubocop:disable Sequel/ConcurrentIndex
+          add_index :name, name: :name, unique: true
+          # rubocop:enable Sequel/ConcurrentIndex
+        end
+      end
+    elsif database_type == :postgres
+      unless indexes(:quota_definitions).include?(:quota_definitions_name_key)
+        alter_table :quota_definitions do
+          add_unique_constraint :name, name: :quota_definitions_name_key
+        end
+      end
+    end
+  end
+end

spec/migrations/20240808118000_drop_unique_constraint_quota_definitions_name_key_spec.rb

@@ -0,0 +1,121 @@
+require 'spec_helper'
+require 'migrations/helpers/migration_shared_context'
+
+RSpec.describe 'migration to add or remove unique constraint on name column in quota_definitions table', isolation: :truncation, type: :migration do
+  include_context 'migration' do
+    let(:migration_filename) { '20240808118000_drop_unique_constraint_quota_definitions_name_key_spec.rb' }
+  end
+  describe 'up migration' do
+    context 'mysql' do
+      before do
+        skip if db.database_type != :mysql
+      end
+
+      it 'removes the unique constraint' do
+        expect(db.indexes(:quota_definitions)).to include(:name)
+        expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true) }.not_to raise_error
+        expect(db.indexes(:quota_definitions)).not_to include(:name)
+      end
+
+      context 'unique constraint on name column does not exist' do
+        before do
+          db.drop_index :quota_definitions, :name, name: :name
+        end
+
+        it 'does not throw an error' do
+          expect(db.indexes(:quota_definitions)).not_to include(:name)
+          expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true) }.not_to raise_error
+          expect(db.indexes(:quota_definitions)).not_to include(:name)
+        end
+      end
+    end
+
+    context 'postgres' do
+      before do
+        skip if db.database_type != :postgres
+      end
+
+      it 'removes the unique constraint' do
+        expect(db.indexes(:quota_definitions)).to include(:quota_definitions_name_key)
+        expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true) }.not_to raise_error
+        expect(db.indexes(:quota_definitions)).not_to include(:quota_definitions_name_key)
+      end
+
+      context 'unique constraint on name column does not exist' do
+        before do
+          db.alter_table :quota_definitions do
+            drop_constraint :quota_definitions_name_key
+          end
+        end
+
+        it 'does not throw an error' do
+          expect(db.indexes(:quota_definitions)).not_to include(:quota_definitions_name_key)
+          expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true) }.not_to raise_error
+          expect(db.indexes(:quota_definitions)).not_to include(:quota_definitions_name_key)
+        end
+      end
+    end
+  end
+
+  describe 'down migration' do
+    before do
+      Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true)
+    end
+
+    context 'mysql' do
+      before do
+        skip if db.database_type != :mysql
+      end
+
+      it 'adds the unique constraint' do
+        expect(db.indexes(:quota_definitions)).not_to include(:name)
+        expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index - 1, allow_missing_migration_files: true) }.not_to raise_error
+        expect(db.indexes(:quota_definitions)).to include(:name)
+      end
+
+      context 'unique constraint on name column already exists' do
+        before do
+          Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true)
+
+          db.alter_table :quota_definitions do
+            add_index :name, name: :name
+          end
+        end
+
+        it 'does not fail' do
+          expect(db.indexes(:quota_definitions)).to include(:name)
+          expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index - 1, allow_missing_migration_files: true) }.not_to raise_error
+          expect(db.indexes(:quota_definitions)).to include(:name)
+        end
+      end
+    end
+
+    context 'postgres' do
+      before do
+        skip if db.database_type != :postgres
+      end
+
+      it 'adds the unique constraint' do
+        expect(db.indexes(:quota_definitions)).not_to include(:quota_definitions_name_key)
+        expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index - 1, allow_missing_migration_files: true) }.not_to raise_error
+        expect(db.indexes(:quota_definitions)).to include(:quota_definitions_name_key)
+      end
+
+      context 'unique constraint on name column already exists' do
+        before do
+          Sequel::Migrator.run(db, migrations_path, target: current_migration_index, allow_missing_migration_files: true)
+
+          db.alter_table :quota_definitions do
+            add_unique_constraint :name, name: :quota_definitions_name_key
+          end
+        end
+
+        it 'does not fail' do
+          expect(db.indexes(:quota_definitions)).to include(:quota_definitions_name_key)
+          expect { Sequel::Migrator.run(db, migrations_path, target: current_migration_index - 1, allow_missing_migration_files: true) }.not_to raise_error
+          expect(db.indexes(:quota_definitions)).to include(:quota_definitions_name_key)
+        end
+      end
+    end
+  end
+end