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, 8 insertions, 0 deletions

diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index d03943ba4a..706964090e 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -379,6 +379,14 @@ The MySQL adapter adds one additional configuration option:
 
 * `ActiveRecord::ConnectionAdapters::Mysql2Adapter.emulate_booleans` controls whether Active Record will consider all `tinyint(1)` columns as booleans. Defaults to `true`.
 
+The PostgreSQL adapter adds one additional configuration option:
+
+* `ActiveRecord::ConnectionAdapters::PostgreSQLAdapter.create_unlogged_tables`
+  controls whether database tables created should be "unlogged," which can speed
+  up performance but adds a risk of data loss if the database crashes. It is
+  highly recommended that you do not enable this in a production environment.
+  Defaults to `false` in all environments.
+
 The SQLite3Adapter adapter adds one additional configuration option:
 
 * `ActiveRecord::ConnectionAdapters::SQLite3Adapter.represent_boolean_as_integer`