Normalization eliminates redundancy and anomalies. 1NF requires atomic values—no arrays in columns. 2NF eliminates partial dependencies—all non-key columns depend on entire primary key. 3NF removes transitive dependencies—non-key columns don't depend

Transactions ensure data consistency through ACID properties. Atomicity guarantees all-or-nothing execution. Consistency maintains database constraints. Isolation prevents concurrent transaction interference. Durability persists committed changes. I u

EXPLAIN reveals database execution plans. I use EXPLAIN ANALYZE for actual runtime statistics. Understanding plan nodes—Seq Scan, Index Scan, Nested Loop, Hash Join—guides optimization. Cost estimates predict query expense. Rows estimates show expecte

PostgreSQL JSONB stores binary JSON efficiently with indexing support. I use JSONB for semi-structured data, dynamic attributes, event logs. JSONB operators enable querying nested data—->, ->>, @>, ?. GIN indexes accelerate JSONB queries.

CTEs improve query readability and maintainability. WITH clauses define named subqueries referenced in main query. I use CTEs to break complex queries into logical steps. Recursive CTEs handle hierarchical data—org charts, category trees, graph traver

Window functions perform calculations across row sets without grouping. ROWNUMBER assigns unique sequential numbers. RANK/DENSERANK handle ties differently. I use PARTITION BY to reset calculations per group. ORDER BY determines calculation order with

Indexes dramatically speed up queries but slow down writes. B-tree indexes handle equality and range queries—default for most databases. I create indexes on foreign keys, frequently queried columns, and WHERE/ORDER BY clauses. Composite indexes order

SQL joins combine data from multiple tables. INNER JOIN returns matching rows only. LEFT/RIGHT JOIN includes all rows from one table, nulls for non-matches. FULL OUTER JOIN combines both. I use CROSS JOIN for Cartesian products sparingly—performance k

Dry-rb provides functional programming tools for Ruby. dry-validation creates complex validation schemas with type checking. dry-types defines strict types—coercion, constraints, sum types. I use dry-struct for immutable data structures with typed att

Refinements provide scoped modifications to existing classes without global monkey patching. I use refinements to add methods to core classes safely. Refinements activate with using statement—scope-limited to file or module. Unlike monkey patches, ref

Ruby 3+ introduces Ractors for true parallelism without GIL limitations. Ractors are isolated actors—no shared mutable state. I use Ractors for CPU-intensive parallel processing. Messages pass between Ractors via send and receive. Async gem provides s

ActionMailer handles email delivery in Rails. Mailers are similar to controllers—actions generate email content. I use ActionMailer for welcome emails, password resets, notifications. Layouts apply consistent styling across emails. Previews enable vie