Spurious constants

PhilHibbs · Post by **PhilHibbs** » Tue Dec 14, 2004 8:08 am

ProfileStage seems to be a little over-zealous at identifying columns as constant. For instance, I have a table with nearly 600,000 rows, and all but 20 of these rows have zero in a particular field. ProfileStage says this is 100% constant. Is this supposed to happen? What is the threshhold for constancy?

chulett · Post by **chulett** » Tue Dec 14, 2004 8:16 am

Sorry, somewhat spurious comment here...

What would you rather it say? 99.9967% constant? (I left off a few 6s, btw) I'm guessing it decided to round it up for you.

Or are you wondering if there is a way to not identify zero as a constant value? To treat it more like a null or unknown value, perhaps?

PhilHibbs · Post by **PhilHibbs** » Tue Dec 14, 2004 8:48 am

chulett wrote:Sorry, somewhat spurious comment here...

What would you rather it say? 99.9967% constant? (I left off a few 6s, btw) I'm guessing it decided to round it up for you.

Or are you wondering if there is a way to not identify zero as a constant value? To treat it more like a null or unknown value, perhaps?

The difference between 99.9967% and 100% is much bigger than the difference between, say, 50% and 75%.

My colleague has resolved the problem by looking at the cardinality instead, a cardinality of 1 indicates a true constant field.