sql

Sometimes raw SQL is the cleanest approach—just keep it safe. Use exec_query with bind params instead of interpolating values. You get both safety and correctness with types.

For queries too complex for the ORM, I use raw SQL. The raw() method returns model instances. I use cursor.execute() for non-model queries. I always use parameterized queries to prevent SQL injection—never string interpolation. For reporting, raw SQL

For leaderboards, let the database do ranking. Window functions are fast and expressive. Use them to compute daily top N without Ruby loops.

Counters are classic race-condition bait. If two requests read, increment, and write, you’ll lose updates under load. I prefer letting Postgres do the atomic work with an upsert: INSERT ... ON CONFLICT ... DO UPDATE to increment the existing value. Th

Some read paths want a denormalized shape without materializing a new table. Postgres views are a clean option. Keep the view definition in a migration and map it with a read-only model.

Not all queries benefit from a full-table index, especially when most rows are ‘inactive’ or archived. A partial index lets you index only the subset you care about (like active users or un-deleted records), which shrinks index size and improves cache