Tom Lane wrote:
> There is not anything in there that considers whether the table's
> physical order is so nonrandom that the search will take much longer
> than it would given uniform distribution. It might be possible to do
> something with the correlation statistic in simple cases ...
In this case, the rows are not random at all, in fact they're inserted from a sequence, then rows are deleted as they
areprocessed. If the planner is hoping for random physical distribution, this particular case is exactly wrong.
Craig