Re: Make query cancellation keys longer

Hi,

I don't have any immediate feedback regarding this patch, but I'm
wondering about one thing related to cancellations - we talk cancelling
a query, but we really target a PID (or a particular backend, no matter
how we identify it).

I occasionally want to only cancel a particular query, but I don't think
that's really possible - the query may complete meanwhile, and the
backend may even get used for a different user connection (e.g. with a
connection pool)? Or am I missing something important?

Anyway, I wonder if making the cancellation key longer (or variable
length) might be useful for this too - it would allow including some
sort of optional "query ID" in the request, not just the PID. (Maybe
st_xact_start_timestamp would work?)

Obviously, that's not up to this patch, but it's somewhat related.



regards

-- 
Tomas Vondra
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