active-record-patterns

Prevent N+1 queries in Rails by applying intentional preloading patterns like `includes` or `preload`. Analyzing your app/models directory helps detect missing preloads and suggests improvements to avoid performance bottlenecks.

Store money fields in Rails migrations using the `decimal` type instead of `float` to prevent data corruption. Active Record patterns enforce this invariant by flagging float-based price columns and suggesting decimal migrations.

Ensure data integrity with transactions and locking in Active Record by keeping invariants inside transactions and using optimistic or pessimistic locks. Proper isolation levels and `after_commit` side-effects prevent race conditions.

Write reversible Rails migrations with safe foreign keys by ensuring reversibility and using concurrent indexes for large tables. This prevents locking issues during deployment and allows safe rollback.

Use pessimistic locking versus optimistic locking in Rails based on race condition probability. Pessimistic locks like `select_for_update` are recommended for billing systems where race conditions exist, while optimistic locking suits low-contention scenarios.

Yes, Active Record pattern analysis works with existing Rails models by scanning `app/models` and typical app directories. It detects money fields, N+1 queries, transaction invariants, and lock usage to suggest improvements.