The JusDB Database Engineering Blog

PostgreSQL offers multiple index types for different access patterns — and choosing wrong means slow queries or wasted space. A comprehensive guide to indexing strategy, from type selection to monitoring and maintenance.

MongoDB indexes fragment over time as documents are inserted, updated, and deleted. Here's how to detect fragmentation, measure its performance impact, and rebuild indexes safely.

Systematically diagnose and fix MySQL 'Too many connections' errors. Learn to identify connection leaks, tune wait_timeout, and implement ProxySQL pooling.

Configure ProxySQL for transparent read/write splitting, connection pooling, and replication lag monitoring. Covers query rules, hostgroups, and stats analysis.

Redis hit maxmemory and evicted your session keys because the application stored 8KB JSON blobs instead of 200-byte hashes. Learn to audit memory usage, use compact encodings, and configure the right eviction policy.

Your PostgreSQL table is 120GB but only contains 40GB of live data. Learn to measure bloat with pgstattuple, understand why autovacuum falls behind, and reclaim space with pg_repack without table locks.

EXPLAIN ANALYZE tells you exactly why your PostgreSQL query is slow, but reading its output is a skill most developers never learn. Learn every node type, identify the five worst plan patterns, and fix them.

Your MySQL instance is at 80% CPU and nobody knows which query is responsible. Learn to enable the slow query log, analyze it with pt-query-digest, and fix the top patterns causing CPU and I/O saturation.

Master MySQL performance optimization with this comprehensive 2025 guide. Learn expert techniques for query tuning, indexing strategies, memory configuration, and InnoDB optimization to achieve 10x database performance improvements.

MongoDB's indexing system supports single-field, compound, multikey, text, geospatial, and partial indexes. Choosing the right index type and key order determines whether your queries use microseconds or seconds.

MySQL transmits data in plaintext by default, exposing passwords and query results to network interception. Here's how to configure SSL/TLS for MySQL — from certificate generation to enforcing encrypted connections.

MySQL 8.0 introduced EXPLAIN FORMAT=TREE — a hierarchical, human-readable query plan format that reveals join order, access methods, and cost estimates in a way that the traditional tabular EXPLAIN cannot.