Update statement running for too long or not

Question

I'm new to working with this much data (20 million rows) and I don't know what I should expect as far as query duration:

update table set field = '1234'  

No index on field. This statement took 25 minutes. The database is set to Simple Recovery. Does 25 minutes seem too long? Table has 9 columns with small data types <50 varchar.

Answer 1

IF you updated 20M rows in one single transaction, then your time was entirely driven by your IO subsystem: what kind of drives you have, what disk files layout etc. If you have 40 spindles in raid 10 with 4 balanced files and a separate similar battery for the log then the result is worryingly slow. If you tested this with one single MDF that shares the spindle with the LDF on a single consumer quality 5000rpm HDD then your time is amazingly fast.

Answer 2

You are updating 20 Mio records in about 1500s averaging at somrthing of 7000 updates per second. Sounds about right.