Data Engineer

We are a SaaS company in travel/aviation technology with multiple database systems (PostgreSQL on Aurora, Firestore, Redshift) that have accumulated tenant configuration drift, schema divergence, and ad-hoc operational practices. We need a Senior DBA to professionalize how we govern data, optimize queries, manage schema changes, and coordinate a complex legacy-to-new system migration currently in flight. This is a hands-on contractor role. You will write SQL, build tooling, audit schemas, optimize queries, and mentor engineers. Current state we need to improve - Multiple database systems without unified governance - Tenant configuration has drifted across customers - One engineer is the de facto bottleneck for ad-hoc database operations - Legacy-to-new migration in progress without tooling to validate data parity - Schema migrations applied via PRs with informal review - Index governance is ad-hoc - Query optimization is reactive - Backup and failover scenarios not regularly tested - No clear tenant data lifecycle policy What you will do Schema audit and tenant drift mapping - Inventory all database systems and document ownership - Map tenant configuration divergence across customers - Identify shadow schema patterns - Produce a tenant drift remediation roadmap Index governance and query optimization - Audit existing indexes; remove cruft, add missing - Identify top 20 slow queries and remediate - Establish index review process for new proposals Migration parity tooling - Build shadow comparison tooling between legacy and new systems - Validate migration parity per tenant - Document graduation procedures and rollback strategies - Replace ad-hoc Slack SQL backfills with proper tooling (PR-based, audited, approved) Operational discipline - Validate backup and point-in-time recovery - Test database failover scenarios - Tune connection pools per service - Document operational runbooks - Mentor 2-3 engineers on database practices Required skills - 8+ years database administration or database reliability engineering - Deep PostgreSQL expertise (Aurora Serverless v2 preferred) - AWS data services: RDS, Aurora, Redshift, DMS - Schema migration tooling (dbmate, Flyway, Liquibase, or similar) - Multi-tenant data architecture patterns - Query optimization at scale: explain plans, indexes, partitioning - Strong SQL plus Python or TypeScript scripting - Backup and disaster recovery strategy design - Connection pooling, replication, high availability Nice to have - Aviation, travel, or fintech domain experience - Multi-store environments (PostgreSQL + NoSQL + warehouse) - Schema-as-code experience - Change Data Capture patterns for migration parity - Experience as first or second DBA hire at a growing company What success looks like - Schema documentation: every critical table documented with owner, retention, access patterns - Tenant drift map with prioritized remediation plan - Index governance process active and followed - Top 20 slow queries identified and remediated - Migration parity tooling working for top critical data flows - Backfill workflow replaced with proper tooling - 2-3 engineers comfortable owning database practices independently Application Please include in your proposal: 1. Two or three examples of prior schema governance or migration coordination work, with measurable outcomes 2. One complex query optimization project with before/after metrics 3. Your preferred approach for validating data parity during a legacy-to-new migration 4. One concrete suggestion for detecting tenant configuration drift in a multi-tenant SaaS 5. Your availability and time zone Working style - Daily brief async updates - Weekly 1:1 with VP of Engineering - Bi-weekly progress review We value directness, written documentation, sustainable pace, clarity over volume. We avoid meetings without agenda and lone-wolf patterns.