Faith & Code | Reflections by Errong

How We Optimized a Spring Boot Pagination Query by 36× (From 1.8 Minutes to 3 Seconds) In high-traffic backend systems, slow database queries are often the hidden bottleneck that quietly kills performance. In our case, a paginated query powering a reporting API was taking 1.8 minutes to respond under load. After optimization, we reduced it to ~3 seconds . 36× faster ~97.2% less execution time ~3500% performance improvement Here’s how we did it — and the key lessons you can apply immediately. 🧱 The Problem: Slow Pagination Query We had a Spring Data JPA query backing a paginated API. It involved multiple filters, joins, and was returning a large dataset. Original issues: Full entity loading Heavy object graph hydration Unnecessary columns fetched Inefficient filtering logic Expensive pagination count The database schema (simplified and anonymized) looked like this: TABLE txn_line ( line_id BIGINT, order_id BIGINT, product_code ...