Add Get ActiveRecord Attribute Directly From Database as a Rails til

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).
 
-_1187 TILs and counting..._
+_1190 TILs and counting..._
 
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@@ -339,6 +339,7 @@ _1187 TILs and counting..._
 ### Heroku
 
 - [Deploy A Review App To A Different Stack](heroku/deploy-a-review-app-to-a-different-stack.md)
+- [Diagnose Problems In A Heroku Postgres Database](heroku/diagnose-problems-in-a-heroku-postgres-database.md)
 - [Set And Show Heroku Env Variables](heroku/set-and-show-heroku-env-variables.md)
 - [SSH Into Heroku Server Hosting App](heroku/ssh-into-heroku-server-hosting-app.md)
 
@@ -591,6 +592,7 @@ _1187 TILs and counting..._
 - [Generate Series Of Numbers](postgres/generate-series-of-numbers.md)
 - [Generating UUIDs With pgcrypto](postgres/generating-uuids-with-pgcrypto.md)
 - [Get A Quick Approximate Count Of A Table](postgres/get-a-quick-approximate-count-of-a-table.md)
+- [Get The Size On Disk of An Index](postgres/get-the-size-on-disk-of-an-index.md)
 - [Get The Size Of A Database](postgres/get-the-size-of-a-database.md)
 - [Get The Size Of A Table](postgres/get-the-size-of-a-table.md)
 - [Get The Size Of An Index](postgres/get-the-size-of-an-index.md)
@@ -720,6 +722,7 @@ _1187 TILs and counting..._
 - [Find Records With Multiple Associated Records](rails/find-records-with-multiple-associated-records.md)
 - [Force All Users To Sign Out](rails/force-all-users-to-sign-out.md)
 - [Generating And Executing SQL](rails/generating-and-executing-sql.md)
+- [Get ActiveRecord Attribute Directly From Database](rails/get-active-record-attribute-directly-from-database.md)
 - [Get An Array Of Values From The Database](rails/get-an-array-of-values-from-the-database.md)
 - [Get An Empty ActiveRecord Relation](rails/get-an-empty-activerecord-relation.md)
 - [Get The Column Names For A Model](rails/get-the-column-names-for-a-model.md)

heroku/diagnose-problems-in-a-heroku-postgres-database.md

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+# Diagnose Problems In A Heroku Postgres Database
+
+Heroku keeps track of all kinds of diagnostics on the performance of your app's
+database. From long running queries and transactions to index cache hit rates
+to unused indexes to tables with bloat.
+
+Running the `pg:diagnose` command for your Heroku app will surface all of these
+details in the terminal.
+
+```bash
+$ heroku pg:diagnose -a APP_NAME
+```
+
+The report will start with the biggest problem areas which it color codes in
+red. If your app is experiencing degraded performance, the list of red items
+would be a good place to start investigating.
+
+The report will then list less urgent problem areas. Those will be color coded
+yellow. Though Heroku has deemed these less serious, you may still want to deal
+with these.
+
+All the other areas of diagnose will fall into the _green_ bucket. Meaning
+Heroku doesn't see any issues in those areas.

postgres/get-the-size-on-disk-of-an-index.md

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+# Get The Size On Disk Of An Index
+
+Indexes, when added to the right columns, can provide massive performance gains
+for certain queries. Indexes aren't free though. It is worth noting that they
+take up disk space. The amount of disk space they take is generally irrelevant,
+but it is at least worth being aware of. Especially if you're deal with a
+massive table.
+
+You can check the current size of an index on disk with [PostgreSQL's
+`pg_relation_size`
+function](https://www.postgresql.org/docs/current/functions-admin.html).
+
+First, you'll want to look up the name of the index you're curious about.
+Running `\d table_name` (replacing `table_name` with the name of the table the
+index is on) will show you everything about the table including its indexes and
+their names.
+
+Then run the following query:
+
+```sql
+select pg_size_pretty(pg_relation_size('index_users_on_email'));
+ pg_size_pretty
+----------------
+ 41 MB
+(1 row)
+```
+
+This one is pretty small. They can get pretty big though. I've seen some that
+take up over 1GB on disk.

rails/get-active-record-attribute-directly-from-database.md

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+# Get ActiveRecord Attribute Directly From Database
+
+In Rails, an ActiveRecord model will automatically get methods named after each
+column in the backing database table. This can be called to retrieve those
+values from the respective columns in the database.
+
+What if you wanted to override and alter one of those values? For example,
+ensure the `email` value you're passing around is always fully downcased.
+
+Something like this won't quite work.
+
+```ruby
+def email
+  email.downcase
+end
+```
+
+Because the method is named `email`, the `email` reference inside it will call
+itself, recursively, until it exceeds the stack.
+
+Instead, you need a way of referencing the email attribute that is stored in
+the database.
+[`attribute_in_database`](https://api.rubyonrails.org/classes/ActiveRecord/AttributeMethods/Dirty.html#method-i-attribute_in_database)
+will do the trick.
+
+```ruby
+def email
+  attribute_in_database('email').downcase
+end
+```
+
+That will retrieve the value from the `email` column in the database for this
+record, downcase it, and return it. Anyone calling `email` won't notice the
+difference.
+
+h/t [Dillon Hafer](https://twitter.com/dillonhafer)