Add Set Statement Timeout For All Postgres Connections as a rails til

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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+_1088 TILs and counting..._
 
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@@ -711,6 +711,7 @@ _1087 TILs and counting..._
 - [Set A Timestamp Field To The Current Time](rails/set-a-timestamp-field-to-the-current-time.md)
 - [Set default_url_options For Entire Application](rails/set-default-url-options-for-entire-application.md)
 - [Set Schema Search Path](rails/set-schema-search-path.md)
+- [Set Statement Timeout For All Postgres Connections](rails/set-statement-timeout-for-all-postgres-connections.md)
 - [Set The Default Development Port](rails/set-the-default-development-port.md)
 - [Show Pending Migrations](rails/show-pending-migrations.md)
 - [Show Rails Models With Pry](rails/show-rails-models-with-pry.md)

rails/set-statement-timeout-for-all-postgres-connections.md

@@ -0,0 +1,39 @@
+# Set Statement Timeout For All Postgres Connections
+
+The
+[`statement_timeout`](postgres/set-a-statement-timeout-threshold-for-a-session.md)
+setting in PostgreSQL allows you to head off long running queries and
+migrations that could break your deploys and lock up your production tables.
+
+This value can be set to a sensible default across all the connections your
+Rails app makes to PostgreSQL. To set it, open up your `config/database.yml`
+file and add a `variables` element to the default section.
+
+```yaml
+default: &default
+  adapter: postgresql
+  encoding: unicode
+  # For details on connection pooling, see Rails configuration guide
+  # https://guides.rubyonrails.org/configuring.html#database-pooling
+  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
+  variables:
+    statement_timeout: 60000
+```
+
+That's 60 seconds in milliseconds. You can avoid the mental math by using a
+string argument with a unit such as `s` for seconds.
+
+```yaml
+  variables:
+    statement_timeout: '60s'
+```
+
+If you then execute a long running query, such as:
+
+```ruby
+ActiveRecord::Base.connection.execute('select pg_sleep(62)')
+```
+
+It will terminate 2 seconds early because of the statement timeout.
+
+[source](https://til.hashrocket.com/posts/b44baf657d-railspg-statement-timeout-)