The JusDB Database Engineering Blog

MySQL 8.0 introduced multi-valued indexes — allowing you to index individual elements of a JSON array so queries using MEMBER OF or JSON_OVERLAPS can use an index.

A production guide to zero-downtime database migrations — why ALTER TABLE causes downtime, the Expand-Contract pattern, safe migration patterns for PostgreSQL and MySQL, and tooling with Flyway, Liquibase, pt-osc, and gh-ost.

Detect query plan regressions in PostgreSQL using auto_explain, pg_hint_plan, and plan baseline management

Use pg_upgrade to migrate between PostgreSQL major versions — upgrade strategies, pre-checks, and rollback plans

ProxySQL pools thousands of application connections into a small backend pool, splits reads to replicas automatically, and lets you change routing without touching application code or restarting MySQL.

Identify bloated indexes in PostgreSQL using pgstattuple, REINDEX CONCURRENTLY, and automated monitoring

PostgreSQL views historically executed with the owner's privileges, bypassing row-level security policies. PostgreSQL 15 fixed this with security_invoker views — here's why it matters and how to use it in multi-tenant schemas.

Tune PostgreSQL checkpoint frequency, WAL segment size, and bgwriter to maximize write throughput

A complete guide to MySQL JSON functions — JSON column type, JSON_EXTRACT and arrow operators, JSON_SET vs JSON_INSERT vs JSON_REPLACE vs JSON_MERGE_PATCH, functional indexes, and multi-valued indexes for arrays.

A deep dive into PostgreSQL JSONB vs JSON storage formats, GIN and B-tree indexing strategies, containment operators, and the performance characteristics that determine which to use for document storage workloads.

A production guide to PostgreSQL full-text search — building tsvector generated columns, GIN indexes, multi-column search with setweight, ts_rank scoring, websearch_to_tsquery, and comparison against Elasticsearch.

A production guide to MySQL full-text search — FULLTEXT index creation, MATCH AGAINST in natural language and boolean modes, the 50% rule, InnoDB vs MyISAM FTS, combining with B-tree indexes, and comparison against Elasticsearch.