Re: SQL:2011 application time

On Wed, Jan 5, 2022 at 11:07 AM Peter Eisentraut <
peter(dot)eisentraut(at)enterprisedb(dot)com> wrote:

> On 21.11.21 02:51, Paul A Jungwirth wrote:
> > Here are updated patches. They are rebased and clean up some of my
> > TODOs.
>
> This patch set looks very interesting. It's also very big, so it's
> difficult to see how to get a handle on it. I did a pass through it
> to see if there were any obvious architectural or coding style
> problems. I also looked at some of your TODO comments to see if I had
> something to contribute there.
>
> I'm confused about how to query tables based on application time
> periods. Online, I see examples using AS OF, but in the SQL standard
> I only see this used for system time, which we are not doing here.
> What is your understanding of that?
>

Paul has previously supplied me with this document
https://cs.ulb.ac.be/public/_media/teaching/infoh415/tempfeaturessql2011.pdf
and that formed the basis of a lot of my questions a few months earlier.

There was similar work being done for system periods, which are a bit
simpler but require a side (history) table to be created. I was picking
people's brains about some aspects of system versioning to see if I could
help bringing that into this already very large patchset, but haven't yet
felt like I had done enough research to post it.

It is my hope that we can at least get the syntax for both application and
system versioning committed, even if it's just stubbed in with
not-yet-supported errors.