The JusDB Database Engineering Blog

How to use pg_stat_statements to identify slow queries, analyze execution stats, and optimize PostgreSQL performance

Five counterintuitive database performance truths every engineer gets wrong — over-indexing costs, N+1 queries, connection pool sizing, replica reads, and EXPLAIN limitations.

TiDB performs schema changes online without blocking reads or writes — using a distributed DDL queue across TiDB nodes. Here's how it works and how to monitor DDL jobs in production.

Understand when MySQL JSON columns help and hurt performance. Learn functional indexes, JSON_TABLE, and when to migrate JSON to normalized columns.

AWS DMS can migrate terabytes of data with zero downtime — but default settings leave significant performance on the table. Here's how to tune DMS for production-grade migrations.

Master InnoDB buffer pool internals: page management, chunk allocation, LRU algorithm, and tuning strategies for maximum cache efficiency.

Survey essential PostgreSQL extensions: pg_stat_statements for query analysis, pg_trgm for fuzzy search, pg_cron for scheduled jobs, pg_buffercache for cache inspection.

Guide MySQL query execution with optimizer hints. Covers INDEX, NO_INDEX, JOIN_ORDER, MAX_EXECUTION_TIME, and query block naming for subquery hint targeting.

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.

The InnoDB redo log default of 100MB is dangerously undersized for production. Learn to measure your write throughput, size innodb_redo_log_capacity correctly, and monitor checkpoint pressure before write stalls occur.

Tune PostgreSQL 18 WAL and checkpoints without weakening crash safety: understand commit modes, measure checkpointer deltas, and validate archive recovery.