But if that theory is correct, this isn't a new
> problem in 9.1, it goes back to 8.3. Have you been running this script
> successfully on older versions?
>
On 9.0.
Though... now that I think about it, I found a bug with the script itself (I
was braindead when I wrote the commandline parser and -pvx did not mean -p
-v -x) that was causing it to not always wrap files in transaction blocks
when it was told to, so it is *possible* 9.0 would be likewise affected...
since the problem only is visible when the index is touched in the same
transaction. I don't have the means to test against it right now, however.
>
> I'm not sure how much we can do to fix this without abandoning the HOT
> optimization, which seems unlikely to go over well. We can certainly
> get it to produce a more helpful error message, and we could very likely
> avoid the failure in more cases than we do now, but in the end it
> remains the case that a newly-built index isn't necessarily usable right
> away, and CLUSTER requires the index to be usable --- else you might
> lose some rows.
>
> regards, tom lane
>