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 (July 2026):

• PostgreSQL 18.4 (EOL 2030-11; May 14, 2026 security release), back-branches: 17.10, 16.14, 15.18, 14.23; PostgreSQL 19 Beta 2 is for testing only
• MongoDB 8.0.26 (GA, EOL 2029-10; June 11, 2026 security release fixing CVE-2026-11933); rapid lane (8.2+) is Atlas-only with a short window - verify live before pinning
• MariaDB 11.8.8 (LTS, EOL 2028-06); 12.x rolling GA is quarterly and EOLs at each successor, with 12.3 the next yearly LTS - verify live
• MySQL 8.4.10 (LTS; June 2026 Critical Security Patch); innovation lane has a short support window - verify live
• SQL Server 2025 RTM + CU7 (released 2026-07-16)
• PgBouncer 1.25.2, Pgpool-II 4.7.2, ProxySQL 3.0.9 (fixes CVE-2026-48772/48773/48774)

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