The JusDB Database Engineering Blog

Use MySQL 8.0 generated columns to index computed values, JSON paths, and date parts. Covers virtual vs stored tradeoffs and functional index patterns.

Use PostgreSQL CTEs and recursive queries for category trees, graph traversal, and complex aggregations. Covers MATERIALIZED vs NOT MATERIALIZED and cycle prevention.

Master MySQL 8.0 window functions for analytical queries. Covers ROW_NUMBER, RANK, LAG/LEAD for period comparison, running totals with SUM OVER, and NTILE quartiles.

PostgreSQL RLS enforces tenant isolation at the database level, bypassing application filtering bugs entirely. Learn to implement RLS policies, index for performance, and test policies before production.

Execute MySQL schema migrations safely with the expand-contract pattern, batched backfills, backward-compatible changes, and migration tooling comparison (Flyway, Liquibase, gh-ost).

ClickHouse MergeTree is why ClickHouse queries 1 billion rows in 0.3 seconds. Learn how parts, merges, and sparse indexes work, and how to choose the ORDER BY key, secondary indexes, and MergeTree variants.

When your events table hits 800 million rows, PostgreSQL declarative partitioning becomes essential. Learn range and hash partitioning, automated management with pg_partman, and zero-downtime archival.

Choose jsonb over json for PostgreSQL: GIN indexing, containment operators, path queries, and update operations with || and jsonb_set. Includes performance comparison.

Use MySQL JSON columns effectively with path operators, functional indexes via generated columns, JSON_CONTAINS filtering, and partial updates with JSON_SET.

Compare three PostgreSQL multi-tenant patterns: shared schema with RLS, schema-per-tenant, and database-per-tenant. Includes hash partitioning for shared schema at scale.

Implement least-privilege access in PostgreSQL with role hierarchies, ALTER DEFAULT PRIVILEGES, schema separation, and privilege auditing queries.

Implement PostgreSQL Row Level Security for multi-tenant isolation. Covers USING clauses, WITH CHECK policies, tenant context via set_config, and performance indexing.