On 01/25/2016 07:22 AM, Tom Lane wrote:
Michael Paquier <michael.paqu...@gmail.com> writes:
On Mon, Jan 25, 2016 at 3:00 PM, Corey Huinker <corey.huin...@gmail.com> wrote:
One thing I discovered in doing this patch is that if you do a timestamp
generate_series involving infinity....it tries to do it. I didn't wait to
see if it finished.


Well, I would think that this is a bug that we had better address and
backpatch. It does not make much sense to use infinity for timestamps,
but letting it run infinitely is not good either.

Meh. Where would you cut it off? AD 10000000000? A few zeroes either
way doesn't really make much difference.

Why cut off? Why not to check if any of the input values is an infinity and simply error out in that case?


If it didn't respond to SIGINT, that would be an issue, but
otherwise this doesn't seem much more exciting than any other way to
create a query that will run longer than you want to wait.

I disagree. Sure, it's possible to construct queries that take forever, but that's difficult (or impossible) to detect at query start. I don't think that means we should not guard against cases that are provably infinite and can't possibly work.

Imagine for example a script that in some rare cases passes happens to pass infinity into generate_series() - in that case I'd much rather error out than wait till the end of the universe.

So +1 from me to checking for infinity.

regard

--
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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