Add support for UNLOGGED Postgresql tables

This commit adds support for the
`ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.create_unlogged_tables`
setting, which turns `CREATE TABLE` SQL statements into
`CREATE UNLOGGED TABLE` statements.

This can improve PostgreSQL performance but at the
cost of data durability, and thus it is highly recommended
that you *DO NOT* enable this in a production environment.

1 files changed, 12 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index a11a786ec7..f701292be3 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -85,6 +85,18 @@ module ActiveRecord
     class PostgreSQLAdapter < AbstractAdapter
       ADAPTER_NAME = "PostgreSQL"
 
+      ##
+      # :singleton-method:
+      # PostgreSQL allows the creation of "unlogged" tables, which do not record
+      # data in the PostgreSQL Write-Ahead Log. This can make the tables faster,
+      # bug significantly increases the risk of data loss if the database
+      # crashes. As a result, this should not be used in production
+      # environments. If you would like all created tables to be unlogged you
+      # can add the following line to your test.rb file:
+      #
+      #   ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.create_unlogged_tables = true
+      class_attribute :create_unlogged_tables, default: false
+
       NATIVE_DATABASE_TYPES = {
         primary_key: "bigserial primary key",
         string:      { name: "character varying" },