Databases: Production Configuration & Operations

Configure, tune, design schemas, migrate, back up, and review database engines - from single-node dev setups to PCI-compliant production clusters. The goal is correct, performant, durable databases that survive failures, pass audits, and don't wake you up at 3am.

Target versions (May 2026):

• PostgreSQL 18.4 (EOL 2030-11; May 2026 security release), previous: 17.10, 16.14
• MongoDB 8.0.20 (GA, EOL 2029-10); rapid lane (8.3 latest) is Atlas-only with a short window - verify live before pinning
• MariaDB 11.8.7 (LTS, EOL 2028-06); 12.x rolling GA is quarterly and EOLs at each successor (12.2 reached EOL 2026-05), with 12.3 the next yearly LTS - verify live
• MySQL 8.4.8 (LTS); innovation lane (9.x) has a short support window - verify live
• SQL Server 2025 RTM + CU3 (GA 2025-11-18)
• PgBouncer 1.25.1, Pgpool-II 4.7.1, ProxySQL 3.0.6

This skill covers six domains depending on context:

• Configuration - engine settings, authentication, TLS, tuning parameters
• Schema design - indexing strategy, partitioning, normalization, type selection
• Migration - cross-engine migration, zero-downtime DDL, ORM migration tooling
• Operations - backup/restore, replication, connection pooling, monitoring
• Performance - query plan analysis, index optimization, vacuum/maintenance
• Compliance - PCI-DSS 4.0 encryption, audit logging, key management, data masking