ActiveRecord equivalent of FULL OUTER JOIN
Need a FULL OUTER JOIN in Rails? Learn why ActiveRecord doesn’t support it natively and the safest Postgres + UNION workarounds for production.
9 min read
SQL to ActiveRecord
Practical guides for converting raw SQL queries into correct, performant ActiveRecord code, including edge cases where Rails behaves differently than SQL.
7 Production-Safe Ways to Do a SQL `CROSS JOIN` in Rails (and When You Actually Should)
Need an ActiveRecord cross join? Learn when SQL CROSS JOIN is justified, how to express it in Rails safely, and how to avoid row explosions in production.
7 min read
LEFT JOIN + WHERE in ActiveRecord: The Trap That Turns It Into INNER JOIN
LEFT JOIN queries often break the moment you add a WHERE on the joined table—silently turning into INNER JOIN behavior. Learn the correct Rails patterns (ON vs WHERE, scoped associations, where.missing/where.associated, EXISTS) and how to verify generated SQL.
5 min read
ActiveRecord Equivalent of SQL CROSS JOIN (And When You Actually Need It)
How to do a SQL CROSS JOIN from ActiveRecord safely: when it’s the right tool, how to express it without losing bind params, and how to avoid accidental Cartesian products.
4 min read
,%20shot%20on%20Canon%20EOS%20R5,%20shallow%20depth%20of%20field%20f_2..jpg)
ActiveRecord INNER JOIN with Multiple Conditions (Without Lying to Yourself)
How to express INNER JOINs with multiple conditions in Rails without changing semantics by accident. Learn when Rails puts predicates in WHERE vs ON, how merge/default_scope can surprise you, and the patterns that stay correct when you later switch to LEFT JOIN.
5 min read
N+1 Isn’t a Rails Problem: It’s a Query-Shaping Problem
Copied SQL into Rails and still got N+1? Rewrote in ActiveRecord and still got N+1? The fix is a set-based mental model: where N+1 really comes from, how to verify it, and the AR patterns that eliminate it safely.
5 min read
Why ActiveRecord Exists: The SQL Mental Model That Breaks in Rails
If you know SQL, ActiveRecord can feel pointless—until it saves you from consistency bugs. Here’s the mental model: where SQL alone breaks app invariants, and how to use AR without losing performance.
5 min read