Merge 295fe153ad into 1f039a8958

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1574 TILs and counting..._
+_1576 TILs and counting..._
 
 See some of the other learning resources I work on:
 - [Ruby Operator Lookup](https://www.visualmode.dev/ruby-operators)
@@ -199,6 +199,7 @@ See some of the other learning resources I work on:
 - [Check The Status of All Services](devops/check-the-status-of-all-services.md)
 - [Check The Syntax Of nginx Files](devops/check-the-syntax-of-nginx-files.md)
 - [Connect To An RDS PostgreSQL Database](devops/connect-to-an-rds-postgresql-database.md)
+- [Default Rails Deploy Script On Hatchbox](devops/default-rails-deploy-script-on-hatchbox.md)
 - [Determine The IP Address Of A Domain](devops/determine-the-ip-address-of-a-domain.md)
 - [Hatchbox Exports Env Vars With asdf](devops/hatchbox-exports-env-vars-with-asdf.md)
 - [Path Of The Packets](devops/path-of-the-packets.md)
@@ -780,6 +781,7 @@ See some of the other learning resources I work on:
 - [Convert A String To A Timestamp](postgres/convert-a-string-to-a-timestamp.md)
 - [Count How Many Records There Are Of Each Type](postgres/count-how-many-records-there-are-of-each-type.md)
 - [Count Records By Type](postgres/count-records-by-type.md)
+- [Count The Number Of Items In An Array](postgres/count-the-number-of-items-in-an-array.md)
 - [Count The Number Of Trues In An Aggregate Query](postgres/count-the-number-of-trues-in-an-aggregate-query.md)
 - [Create A Cluster In A Specific Data Directory](postgres/create-a-cluster-in-a-specific-data-directory.md)
 - [Create A Composite Primary Key](postgres/create-a-composite-primary-key.md)

devops/default-rails-deploy-script-on-hatchbox.md

@@ -0,0 +1,28 @@
+# Default Rails Deploy Script On Hatchbox
+
+I deployed a Rails app to [Hatchbox](https://hatchbox.io) recently. When
+following along in the log during a deploy, I can see most of what is happening
+as part of the deploy. Though it is too verbose to look through every line. I'd
+rather see the contents of the deploy script.
+
+I did quite a bit of digging around while SSH'd into my hatchbox server, but I
+couldn't find if or where that file might be stored.
+
+Instead, there is a [_Help Center_
+article](https://hatchbox.relationkit.io/articles/55-what-is-the-default-rails-deploy-script)
+where Chris Oliver shares what is in the script.
+
+```bash
+bundle install -j $(nproc)
+yarn install
+bundle exec rails assets:precompile
+[[ -n "${CRON}" ]] && bundle exec rails db:migrate
+```
+
+It does a parallelized `bundle install`, then a `yarn install` (make sure your
+project is using `yarn.lock`), Rails asset precompilation, and then if `CRON`
+is set (Cron role is available by checking _Cron_ under _Server
+Responsibilities_ for your Hatchbox server), it will run Rails migrations.
+
+From app settings, the deploy script can be overridden, or pre- and post-deploy
+steps can be added.

postgres/count-the-number-of-items-in-an-array.md

@@ -0,0 +1,56 @@
+# Count The Number Of Items In An Array
+
+There are two ways to count the number of items in an array with PostgreSQL.
+The one that might jump out at you or show up at the top of search results is
+[`array_length`](https://www.postgresql.org/docs/current/functions-array.html).
+
+```sql
+> select array_length(array[1,2,3], 1);
++--------------+
+| array_length |
+|--------------|
+| 3            |
++--------------+
+
+> select array_length(array[[1,2], [3,4]], 2);
++--------------+
+| array_length |
+|--------------|
+| 2            |
++--------------+
+```
+
+This requires specifying the dimension at which you want to check the length.
+The first example, checking the 1st dimension of a one-dimensional array, seems
+like the more common and useful scenario. In the second example, we are
+checking the 2nd dimension.
+
+The other way we can determine the number of items in an array is with the
+[`cardinality`](https://www.postgresql.org/docs/current/functions-array.html)
+function.
+
+> Returns the total number of elements in the array, or 0 if the array is
+> empty.
+
+```sql
+> select cardinality(array[1,2,3]);
++-------------+
+| cardinality |
+|-------------|
+| 3           |
++-------------+
+
+> select cardinality(array[[1,2], [3,4]]);
++-------------+
+| cardinality |
+|-------------|
+| 4           |
++-------------+
+```
+
+This behaves the same as `array_length` for a one-dimensional array and doesn't
+require a second argument. Where it gets more interesting is with
+multi-dimensional arrays. It returns the total number of elements in the
+arrayregardless of the nesting.
+
+[source](https://mattrighetti.com/2025/01/20/you-dont-need-sql-builders)