postgresql

Database security protects data from unauthorized access. I use GRANT/REVOKE for permissions—SELECT, INSERT, UPDATE, DELETE. Role-based access control groups permissions. Row-level security filters data per user. Column-level security restricts sensit

Recursive CTEs traverse hierarchical data—org charts, category trees, graphs. I use WITH RECURSIVE for self-referential queries. Base case provides starting rows. Recursive case joins to previous iteration. Understanding termination prevents infinite

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

Database testing ensures schema and queries work correctly. I use transactions for test isolation—rollback after each test. Test fixtures provide consistent data. Factory patterns generate test data programmatically. Understanding schema migrations in

Partitioning splits large tables into smaller physical pieces. Range partitioning divides by value ranges—dates, IDs. List partitioning groups by specific values—regions, categories. Hash partitioning distributes evenly across partitions. I use partit

Constraints enforce data integrity at the database level. PRIMARY KEY ensures uniqueness and identifies rows. FOREIGN KEY maintains referential integrity. NOT NULL prevents null values. UNIQUE prevents duplicates. CHECK validates data conditions. DEFA

Database best practices ensure reliability and performance. I follow normalization principles—minimize redundancy. Use appropriate indexes—not too many, not too few. Implement constraints for data integrity. Choose correct data types for efficiency. R

SaaS applications serving multiple customers (tenants) need data isolation to prevent cross-tenant data leaks. The apartment gem provides schema-based multi-tenancy for PostgreSQL where each tenant gets a separate schema, ensuring complete database-le

Performance monitoring identifies slow queries and bottlenecks. I use EXPLAIN ANALYZE to profile query execution. pgstatstatements tracks query statistics over time. Slow query logs capture problematic queries. Query execution time, I/O, and buffer us

Proper indexing is the difference between millisecond and multi-second query response times. I add indexes to foreign keys automatically since Rails doesn't do this by default, and I create composite indexes for common query patterns that filter on mu

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

Query debugging identifies performance and correctness issues. I use EXPLAIN ANALYZE to understand execution plans. Slow query logs reveal problematic queries. pgstatstatements tracks query statistics. Understanding sequential scans vs index scans hel