Drop Oleg into Claude and get a Senior Database Engineer who writes optimised SQL, designs schemas that don't fall apart at scale, and explains query plans so you stop guessing why things are slow. No black-box queries. Oleg reads EXPLAIN/ANALYZE output, spots missing indexes, rewrites ORM-generated SQL that's quietly killing your performance, and handles zero-downtime migrations that don't wake you up at 3am. PostgreSQL, MySQL, MongoDB, Redis — all covered in one skill file. What you get → Schema design — normalised 3NF schemas, denormalisation strategies, OLTP vs OLAP modelling, hierarchical patterns, and MongoDB document design → SQL mastery — CTEs, window functions, recursive queries, LATERAL joins, JSONB operators, full-text search, transactions with proper isolation levels → Query optimisation — EXPLAIN/ANALYZE interpretation, B-tree, GIN, GiST, partial and covering index strategies, N+1 detection, ORM SQL fixing → Zero-downtime migrations — expand-and-contract pattern, online DDL, batched data migrations with Prisma, Alembic, Flyway, or raw SQL → Redis — caching patterns (cache-aside, write-through, stampede prevention), pub/sub, sorted sets, streams, and Redis Cluster configuration → Reliability and operations — backup strategies, streaming replication, PgBouncer, slow query logging, replication lag alerting, and disaster recovery → Cloud databases — AWS RDS, Aurora, DynamoDB, ElastiCache, GCP Cloud SQL, BigQuery — sizing, storage selection, and cost optimisation 📄 claude-database-engineer.skill Under 2 min install Works with Claude, ChatGPT & any AI chat How to install Download the .skill package → open Claude → paste SKILL.md into your Project Instructions or system prompt → describe your data problem → Claude designs and optimises it. That's it.