Track · 2:49 · Liner note
Slow Rollup
A rollup pre-aggregates detailed data into summaries such as daily totals, and a slow rollup is one that takes too long because of data volume or an inefficient query.
The rollup that finished in four minutes last year now takes most of the morning. Nothing is wrong in a way the logs will admit. Slow Rollup is the sign that data volume has outgrown a design that once looked fine.
Before adding hardware, read the plan. Is it rescanning history? Could it be incremental, or partitioned by day, or computed from a narrower table? Most slow rollups are a modeling problem in disguise. Make the job touch only what changed, and the morning comes back.