Estimating Statistics > 50%

Hello everyone. This is an issue that has always bothered me when reading the Oracle documentation on estimating statistics for the CBO. I am sure that this may have been talked about in the archives but was unable to find anything.

In the SQL guide while defining the "analyze" command, it indicates that you can estimate statistics by providing a "sample" of the data to collect stats for. One comment they provide is:

"If you specify more than half of the data, then Oracle reads all the
data and computes the statistics."

Well, what about the "percent" option and its range of 1 .. 99? Why would you specify *any* value >= 50% since by their comment, it would compute stats rather than estimate them?

My assumption is that this comment only applies to sampling using the
"rows" option and not the "percent" option.

Am I correct in this assumption?

Thanks in advance to everyone!

• jeff