Allow `truncate` for SQLite3 adapter and add `rails db:seed:replant` (#34779)

* Add `ActiveRecord::Base.connection.truncate` for SQLite3 adapter.

SQLite doesn't support `TRUNCATE TABLE`, but SQLite3 adapter can support
`ActiveRecord::Base.connection.truncate` by using `DELETE FROM`.

`DELETE` without `WHERE` uses "The Truncate Optimization",
see https://www.sqlite.org/lang_delete.html.

* Add `rails db:seed:replant` that truncates database tables and loads the seeds

Closes #34765

6 files changed, 64 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 9f28fdf749..63e07932d9 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -154,6 +154,10 @@ module ActiveRecord
         @statements.clear
       end
 
+      def truncate(table_name, name = nil)
+        execute "DELETE FROM #{quote_table_name(table_name)}", name
+      end
+
       def supports_index_sort_order?
         true
       end
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 8de06e8466..f021a8f6c4 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/activerecord/lib/active_record/railties/databases.rake
@@ -66,6 +66,11 @@ db_namespace = namespace :db do
     end
   end
 
+  # desc "Truncates tables of each database for current environment"
+  task truncate_all: [:load_config, :check_protected_environments] do
+    ActiveRecord::Tasks::DatabaseTasks.truncate_all
+  end
+
   # desc "Empty the database from DATABASE_URL or config/database.yml for the current RAILS_ENV (use db:purge:all to purge all databases in the config). Without RAILS_ENV it defaults to purging the development and test databases."
   task purge: [:load_config, :check_protected_environments] do
     ActiveRecord::Tasks::DatabaseTasks.purge_current
@@ -223,6 +228,11 @@ db_namespace = namespace :db do
     ActiveRecord::Tasks::DatabaseTasks.load_seed
   end
 
+  namespace :seed do
+    desc "Truncates tables of each database for current environment and loads the seeds"
+    task replant: [:load_config, :truncate_all, :seed]
+  end
+
   namespace :fixtures do
     desc "Loads fixtures into the current environment's database. Load specific fixtures using FIXTURES=x,y. Load from subdirectory in test/fixtures using FIXTURES_DIR=z. Specify an alternative path (eg. spec/fixtures) using FIXTURES_PATH=spec/fixtures."
     task load: :load_config do
diff --git a/activerecord/lib/active_record/tasks/database_tasks.rb b/activerecord/lib/active_record/tasks/database_tasks.rb
index 27e401a756..ef02ca8190 100644
--- a/activerecord/lib/active_record/tasks/database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/database_tasks.rb
@@ -182,6 +182,24 @@ module ActiveRecord
         }
       end
 
+      def truncate_tables(configuration)
+        ActiveRecord::Base.connected_to(database: { truncation: configuration }) do
+          table_names = ActiveRecord::Base.connection.tables
+          internal_table_names = [
+            ActiveRecord::Base.schema_migrations_table_name,
+            ActiveRecord::Base.internal_metadata_table_name
+          ]
+
+          class_for_adapter(configuration["adapter"]).new(configuration).truncate_tables(*table_names.without(*internal_table_names))
+        end
+      end
+
+      def truncate_all(environment = env)
+        ActiveRecord::Base.configurations.configs_for(env_name: environment).each do |db_config|
+          truncate_tables db_config.config
+        end
+      end
+
       def migrate
         check_target_version
 
diff --git a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
index 1c1b29b5e1..f2b4ead98d 100644
--- a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
@@ -31,6 +31,16 @@ module ActiveRecord
         connection.recreate_database configuration["database"], creation_options
       end
 
+      def truncate_tables(*table_names)
+        return if table_names.empty?
+
+        ActiveRecord::Base.connection.disable_referential_integrity do
+          table_names.each do |table_name|
+            ActiveRecord::Base.connection.truncate(table_name)
+          end
+        end
+      end
+
       def charset
         connection.charset
       end
diff --git a/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb b/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
index 8acb11f75f..dc368eb97d 100644
--- a/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
@@ -48,6 +48,18 @@ module ActiveRecord
         create true
       end
 
+      def truncate_tables(*table_names)
+        return if table_names.empty?
+
+        ActiveRecord::Base.connection.disable_referential_integrity do
+          quoted_table_names = table_names.map do |table_name|
+            ActiveRecord::Base.connection.quote_table_name(table_name)
+          end
+
+          ActiveRecord::Base.connection.execute "TRUNCATE TABLE #{quoted_table_names.join(", ")}"
+        end
+      end
+
       def structure_dump(filename, extra_flags)
         set_psql_env
 
diff --git a/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb b/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb
index a82cea80ca..cedbae6b7f 100644
--- a/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/sqlite_database_tasks.rb
@@ -33,6 +33,16 @@ module ActiveRecord
         create
       end
 
+      def truncate_tables(*table_names)
+        return if table_names.empty?
+
+        ActiveRecord::Base.connection.disable_referential_integrity do
+          table_names.each do |table_name|
+            ActiveRecord::Base.connection.truncate(table_name)
+          end
+        end
+      end
+
       def charset
         connection.encoding
       end