The "clustered index" is, for all intents and purposes, the table itself. I would expect that to the majority of the work on a simple update.
In other words, this is normal and expected.
You'll want to take a look at how clustered indexes work. If you'll be administering or performance tuning, you'll need to know about them.
- Gus "GSquared", RSVP, OODA, MAP, NMVP, FAQ, SAT, SQL, DNA, RNA, UOI, IOU, AM, PM, AD, BC, BCE, USA, UN, CF, ROFL, LOL, ETC
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