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.

2 files changed, 18 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb
index 8e381a92cf..ceb8b40bd9 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_creation.rb
@@ -23,6 +23,17 @@ module ActiveRecord
             end
             super
           end
+
+          # Returns any SQL string to go between CREATE and TABLE. May be nil.
+          def table_modifier_in_create(o)
+            # A table cannot be both TEMPORARY and UNLOGGED, since all TEMPORARY
+            # tables are already UNLOGGED.
+            if o.temporary
+              " TEMPORARY"
+            elsif o.unlogged
+              " UNLOGGED"
+            end
+          end
       end
     end
   end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
index 206b855a18..dc4a0bb26e 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
@@ -175,6 +175,13 @@ module ActiveRecord
       class TableDefinition < ActiveRecord::ConnectionAdapters::TableDefinition
         include ColumnMethods
 
+        attr_reader :unlogged
+
+        def initialize(*)
+          super
+          @unlogged = ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.create_unlogged_tables
+        end
+
         private
           def integer_like_primary_key_type(type, options)
             if type == :bigint || options[:limit] == 8