Tag See all →

#analytics

2 stories

Web Development Bug Report

Analytics exit events never arrive: fetch in unload vs sendBeacon on pagehide

John Nguyen · Mar 14, 2026 · 10 min read

Our session-end events showed up for about a third of sessions on desktop and almost none on mobile. The tracker posted with fetch inside an unload handler that browsers cut short or never fire. Flushing on visibilitychange with sendBeacon brought delivery above 97 percent.

Banner: a sliding window frame moving across rows of a table with a rising line chart above

Databases

SQL window functions for real reports: LAG gaps, running totals and frames

John Nguyen · Jan 13, 2025 · 9 min read

Most reporting queries that end up as nested subqueries or app-side loops are one window function away from simple. A practical tour of LAG for gaps, running totals, moving averages and the frame clause defaults that quietly give wrong numbers.