Sangwon Seon
Database Administrator / Database Reliability Engineer
Seoul, South Korea
I am a Database Reliability Engineer with a focus on ensuring database reliability,
performance, and scalability in high-traffic production environments.
My expertise spans ERD design, business data aggregation, query tuning,
data migration, and monitoring & automation across real-world services
serving millions of users.
I approach problems by analyzing root causes from data structure and
execution-flow perspectives, and continuously apply insights from ongoing
learning and hands-on operations to build efficient and stable database systems.
IMWEB is a no-code e-commerce platform serving over 10 million monthly users,
enabling businesses to build websites and online stores without developers
or designers, and providing an end-to-end commerce workflow from orders to shipping.
Since joining the company, I have been working in the Infrastructure team,
focusing on Aurora MySQL database operations, operational automation,
new query reviews, and performance tuning of existing workloads.
I have also designed database schemas for new service launches and built
database monitoring systems to ensure stability and performance in
large-scale production environments.
[Company] No-code e-commerce platform with 10M+ monthly visitors
[Role] Database Reliability Engineer — Aurora MySQL Operations & Optimization (7 months as the sole owner of production DB operations)
━━━ Ownership & Scale ━━━
- Owned end-to-end Aurora MySQL operations for a high-traffic e-commerce platform serving 10M+ monthly users, including availability, performance, cost, and security
- Acted as single DB owner for 7 months, maintaining zero critical database incidents during that period
━━━ Automation & DevOps ━━━
- Led migration of production DB workflows from application-level batch jobs to AWS Lambda-based automation, reducing incident response and deployment time by 60%
- Automated operational DB tasks including: Partition lifecycle management, Backups and capacity control, Test environment provisioning, Account expiration handling
- Built centralized execution notification, monitoring, and logging pipelines to improve operational visibility
- Strengthened security posture by applying KMS encryption and enforcing IAM least-privilege access policies
━━━ Performance Optimization ━━━
- Improved critical Aurora MySQL query performance by 70%+ on average through execution-plan-driven tuning of high-traffic production workloads
- Performed zero-downtime schema and index changes during off-peak hours using Online DDL and PT-OSC
- In emergency scenarios, directly modified and deployed production code under predefined R&R agreements to restore service stability
━━━ Abuse Prevention & Data Hygiene ━━━
- Designed, built, and owned an automated malicious-content prevention system, reducing daily post volume by 90% and lowering Aurora reader CPU utilization by 15%+
- Developed an internal admin interface to manage false positives safely
- Safely deleted 30M+ malicious records without service disruption
━━━ Cost Optimization ━━━
- Achieved 50%+ monthly database cost reduction by: Migrating Aurora Serverless v2 → Provisioned clusters, Purchasing and optimizing Reserved Instances (RI), Applying I/O-Optimized storage to reduce I/O-related costs
- Analyzed RI utilization across accounts and instance families and initiated optimized purchase proposals
━━━ Reliability & Operations ━━━
- Led Aurora MySQL major version upgrade (v2 → v3) with zero post-upgrade incidents
- Analyzed compatibility risks related to character sets and parameters
- Conducted comprehensive query audits using general logs
- Established rollback strategies and real-time monitoring
- Responded to traffic spikes with real-time monitoring and autoscaling
- Performed root cause analysis and immediate remediation during incidents, including unauthorized access and anomalous query behavior
━━━ Data Integrity & Financial Accuracy ━━━
- Conducted monthly PG reconciliations to support cash-basis to accrual-basis revenue aggregation, ensuring financial data accuracy
- Executed safe, guarded data corrections during business hours with zero resource spikes or service impact
- Refactored and corrected legacy datasets to support new business initiatives
━━━ Design & Quality Management ━━━
- Designed new service database schemas and refactored inefficient legacy structures
- Performed comprehensive SQL reviews for all new queries, optimizing indexes and execution paths before production rollout
- Provided engineering teams with code-level guidance aligned with updated data models
- Maintained up-to-date ERD documentation, tracking schema evolution through structured release notes
━━━ Security & Compliance ━━━
- Supported ISMS follow-up audits (2024, 2025) as the primary DB representative
- Conducted DB-related audit interviews, produced monthly inspection reports, and remediated identified findings
━━━ Mentorship & Knowledge Sharing ━━━
- Designed and delivered a DB onboarding and training program for new engineers (ongoing for 2+ years)
- Conducted monthly training sessions covering: Database architecture, Development guidelines, SQL best practices, ERD interpretation and usage
[Company] Maritime IT company specializing in ship radar and camera systems
[Role] Database Engineer — MariaDB & MongoDB Operations and Optimization
━━━ Ownership & Scope ━━━
- Owned MariaDB and MongoDB operations and optimization for maritime surveillance systems, supporting data-intensive radar and camera workloads
- Focused on performance, stability, data modeling, and availability across both relational and document-based databases
━━━ Performance Optimization ━━━
MariaDB — Query & Cache Optimization
- Analyzed and tuned vendor-written SQL queries, improving execution efficiency of production workloads
- Implemented Query Cache strategies, prioritizing high-frequency queries to reduce query latency and database load
MongoDB — Engine & Storage Optimization
- Significantly improved MongoDB stability and performance through storage engine and schema optimizations
- Optimized WiredTiger cache sizing, reduced storage footprint and I/O overhead by adjusting compression algorithms
- Removed unnecessary fields and applied Embedded Document patterns
- Achieved measurable improvements: 99% improvement in server stability, 40% reduction in storage usage, 46% improvement in response times
━━━ Data Modeling & Schema Design ━━━
MariaDB — Schema Refinement
- Refactored database schemas by removing redundant indexes and redesigning efficient indexing strategies
- Improved data integrity and maintainability through normalization, eliminating redundant data
- Introduced common code tables and designed new tables to support additional features
MongoDB — Document Modeling
- Designed indexes based on high-usage field analysis
- Improved data manageability and query efficiency using Embedded Document patterns
━━━ Migration & Data Engineering ━━━
- Led large-scale RDB → MongoDB data migration, improving migration speed by 55% compared to previous approaches
- Developed a Docker container–based real-time migration server to safely handle large data volumes during transition
━━━ High Availability & Replication ━━━
- Configured MariaDB Replication to secure write-server resources and improve overall system stability
- Implemented MongoDB Replica Sets (PSS architecture) to ensure high availability and fault tolerance
━━━ Monitoring & Operational Stability ━━━
- Operated database monitoring systems to ensure stable service operations through proactive resource monitoring
- Implemented slow query monitoring and analysis, enabling early detection and resolution of performance degradation
[Company] Consumer finance company specializing in lending services
[Role] Backend Engineer — Data-centric system development & automation
━━━ System Development & Domain Support ━━━
- Supported core financial systems as a backend engineer, with a strong focus on data processing logic, database-driven workflows, and batch-based backend services
- Contributed to backend development for credit evaluation, lending operations, and internal financial data pipelines in a compliance-sensitive environment
━━━ Credit Scoring Platform ━━━
Personal Credit Scoring System (2021 Credit Score System Introduction)
- Participated in the launch of a new credit score–based evaluation platform, contributing to the transition from credit grade–based logic to numeric credit scoring
- Contributed to backend implementation of:
• Application Scoring System (ASS): Integrated NICE credit bureau data for customer credit evaluation
• Behavior Scoring System (BSS): Implemented procedure-based large-scale data extraction and aggregation pipelines
- Assisted in core system refactoring to support new scoring logic and evaluation flows
━━━ Automation & Backend Processing ━━━
Virtual Account Migration Automation
- Implemented a batch-driven backend module to automate virtual account migration during borrower changes
- Reduced manual coordination and processing across related departments, shortening overall business workflows by approximately 33%
Batch & Procedure Development
- Wrote and optimized SQL queries and stored procedures to support recurring data requests and internal reporting needs
- Designed procedure management tables and implemented result monitoring to improve batch execution reliability
━━━ Data Management & Compliance ━━━
- Implemented backend logic supporting personal data retention and destruction policies in accordance with regulatory requirements
- Participated in quarterly large-scale data deletion operations and coordinated post-deletion reorganization (Reorg) processes
- Supported ongoing maintenance of large-scale financial system datasets to ensure data consistency and operational stability