Active DBA · Enterprise Engagements

Emre Kaçar

DATABASE ADMINISTRATOR

Oracle Database 19c/21c • PL/SQL Engineering • PostgreSQL Optimization

Architecting mission-critical database systems with zero data loss. Specialized in reducing query execution times from 45s → 120ms through deep execution plan analysis, indexing strategies, and partitioning architectures. Currently driving hospital-wide data migration and high-availability database engineering at SISOFT.

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Query Optimization
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Downtime Incidents
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Avg. Response Time
View Selected Work GitHub LinkedIn
sqlplus — emre@PROD_DB — EXPLAIN PLAN
LIVE
SQL*Plus: Release 19.0.0.0.0 - Production
Connected to: Oracle Database 19c Enterprise Edition
Session ID: 847 | Host: db-hospital-cluster-01
 
SQL> █
PROD_DB: ACTIVE
| SGA: 4.2 GB | 00:00:00
02 ENGINEERING DOMAIN

Core Competencies

Deep expertise in relational database architecture, mission-critical operations, and low-level performance tuning across enterprise environments.

RDBMS

Core Databases

High availability, cluster maintenance, and transactional integrity across modern database engines.

Oracle Database 19c / 21c PostgreSQL 14 / 15 / 16 Neon.tech Cloud DB MySQL 8.0 Redis (Caching)
Tuning & Code

Database Engineering & Tuning

Kernel-level optimization, index architectures, stored program units, and data partition design.

PL/SQL Packages & Triggers Execution Plan (Cost Tuning) EXPLAIN ANALYZE B-Tree, Hash & GIN Indexing Range & List Partitioning Materialized Views ERD & Data Modeling
Migration

Data Pipeline & Systems

Zero-downtime data migration, verification query suites, Linux server administration, and automation.

Zero-Downtime Live Migration PL/SQL Validation Suites ETL Operations Linux CLI & Bash Scripting Dockerized Database Labs Git & CI/CD Pipelines
Monitoring

Monitoring & Diagnostics

Continuous telemetry, lock contention diagnosis, buffer pool tuning, and bottleneck isolation.

Oracle Enterprise Manager Toad for Oracle pgAdmin & psql DBeaver Enterprise TKPROF & AWR Reports pgaudit Security
03 INTERACTIVE CONSOLE

SQL Performance Lab

Execute live telemetry and query plan scenarios directly in the simulated database shell. Observe real execution costs and index impact.

emre@enterprise-db: ~ (bash / psql / sqlplus)
CONNECTED

// Connected to Enterprise PostgreSQL 16 & Oracle 19c EE cluster

// Target: neon.tech AWS eu-central-1 | Session: ANALYST_PROD

// System date: -- | Click a scenario below

postgres=# SELECT * FROM v$instance; █ 
Click any scenario button below to simulate execution plans, PL/SQL engine audits, and storage statistics in real time.
SELECT SCENARIO:
04 SELECTED WORK

Selected Work (03)

Production database architectures, benchmarking laboratories, and zero-leak security modules.

PG_OPTIMIZER NEON.TECH AWS
SQL> EXPLAIN ANALYZE SELECT * FROM orders OPTIMIZED
EXECUTION VERDICT 99.7% Slashed ↗ INDEX RANGE SCAN
118ms FROM 45s
B-TreeBRINGINWork Mem
COST REDUCED: 45230 → 38 | 847K ROWS

Enterprise PostgreSQL Optimization

High-volume query optimization laboratory deployed on cloud PostgreSQL. Benchmarking full table scans against compound B-Tree and GIN indexes, optimizing buffer cache hits, and refactoring expensive JOINs.

EXPLAIN ANALYZEPostgreSQL 16Index Tuning
ORACLE_PLSQL 19c / 21c EE
PL/SQL> PKG_HR_INTELLIGENCE.EXECUTE_AUDIT() COMPILED
PACKAGE MODULES 12+ Packages ↗ AUTONOMOUS TRX
100% AUDIT LOGGED
Bulk CollectRef CursorsTriggersDynamic SQL
ZERO BUSINESS LOGIC LEAK OUTSIDE DATABASE ENGINE

PL/SQL Enterprise HR & DB Intelligence

End-to-end PL/SQL architecture executing complex business rules directly inside Oracle Database. Modular package structures, autonomous audit trails, and bulk processing optimizations.

Oracle 19c/21cPL/SQL PackagesDatabase Engine
DB_SECURITY ZERO-LEAK
SEC> ENFORCE ROW LEVEL SECURITY (RLS) ACTIVE
SECURITY VERDICT Tenant Isolated ↗ MULTI-TIER RBAC
0Leaks PGAUDIT ON
Row-Level SecuritypgauditMaskingSSL/TLS
COMPLIANT WITH SENSITIVE HEALTHCARE & FINTECH DATA

PostgreSQL Security, RBAC & Audit Lab

Enterprise security blueprint implementing Row-Level Security (RLS), multi-tenant isolation, least-privilege role hierarchies, and forensic audit logging with pgaudit.

RLS SecurityMulti-TenantAudit Compliance
05 CAREER TIMELINE

Experience & Career

Production database management, zero-downtime migration, and systems engineering track record.

Database & Migration Specialist

SISOFT Healthcare Information Systems CURRENT ROLE
March 2025 — Present Ankara, TR · Full-time

Driving end-to-end database transformation and live migration for enterprise hospital information systems. Ensuring zero data loss and minimal go-live maintenance windows across millions of clinical records.

  • Authored mission-critical Oracle PL/SQL data validation packages to guarantee referential integrity and data reconciliation before live switchovers.
  • Conducted performance tuning and execution plan analysis (AWR/TKPROF) on slow-running clinical queries, slashing peak transaction bottlenecks.
  • Managed large-scale schema migrations, table partitioning, and constraint indexing across distributed hospital database nodes.
Oracle 19c/21c PL/SQL Packages Data Migration Execution Plan Tuning Healthcare IT Toad / SQL*Plus

Systems Engineering Intern

WGUARD INTERNSHIP
2024 Ankara, TR

Linux server administration, system security hardening, and infrastructure monitoring across server fleets.

  • Automated recurring maintenance tasks and log rotation via Bash shell scripts and cron daemon.
  • Monitored disk I/O, memory allocations, and network socket utilization in production Linux environments.
Linux Administration Bash Scripting Server Hardening System Monitoring

Backend & Database Query Intern

ELSIFY Software INTERNSHIP
2023 — 2024 Hybrid

Designed relational database schemas, written optimized SQL queries, and integrated backend Java services with PostgreSQL data layers.

  • Eliminated N+1 query antipatterns and designed multi-column indexes for frequently queried endpoints.
PostgreSQL SQL Query Optimization Schema Design Java Spring

Data Analytics & Relational Databases Immersive

GoIT & Computer Engineering Studies ENROLLED
Aralık 2025 — Haziran 2026 Turkey

In-depth program focused on relational algebra, complex SQL transformations, data aggregation, and database administration fundamentals.

Advanced SQL Relational Algebra Data Modeling
06 CREDENTIALS

Certifications & Badges

Industry-recognized certifications validating database engineering, Linux administration, and analytics.

HackerRank SQL (Advanced)

Complex SQL, Window Functions, Index-Driven Queries

HackerRank Certified

SQL & Relational Databases 101

Relational Database Theory, Normalization & DDL/DML

IBM / Cognitive Class

Linux Essentials

Linux Kernel, File Permissions, Bash & Process Mgmt

Cisco Networking Academy / NDG

Data Analytics Essentials

Data Transformations, Statistical Analysis & Pipelines

Cisco Networking Academy

Data Analytics Immersive

Enterprise SQL, BI Dashboards & Data Architecture

GoIT International
SQL> SELECT status, contact FROM dba_availability WHERE status = 'OPEN';

Let's Connect for Enterprise Database Excellence

Available for enterprise database administration, Oracle PL/SQL engineering, PostgreSQL performance audits, and high-impact data migration projects.

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