Robert Haas <robertmhaas@gmail.com> writes:
> Except that's not how it works. At least in the case of ANALYZE, we
> *aren't* counting all the tuples in the table. We're selecting a
> random sample of pages and inferring a tuple density, which we then
> extrapolate to the whole table and store. Then when we pull it back
> out of the table, we convert it back to a tuple density. The real
> value we are computing and using almost everywhere is tuple density;
> storing a total number of tuples in the table appears to be just
> confusing the issue.
If we were starting in a green field we might choose to store tuple
density. However, the argument for changing it now is at best mighty
thin; IMO it is not worth the risk of breaking client code.
regards, tom lane
