Re: Add sub-transaction overflow status in pg_stat_activity

"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> On Mon, Nov 14, 2022 at 9:41 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> The overhead of fetching the information is not large, but Justin is
>> concerned about the effect on the display width. I feel that's kind of
>> a lost cause because it's so wide already anyway, but I don't see a
>> reason why we need *two* new columns. Can't we get by with just one?
>> It could be overflowed true/false, or it could be the number of
>> subtransaction XIDs but with NULL instead if overflowed.

> NULL when overflowed seems like the opposite of the desired effect, calling
> attention to the exceptional status. Make it a text column and write
> "overflow" or "###" as appropriate. Anyone using the column is going to
> end up wanting to special-case overflow anyway and number-to-text
> conversion aside from overflow is simple enough if a number, and not just a
> display label, is needed.

I'd vote for just overflowed true/false. Why do people need to know
the exact number of subtransactions? (If there is a use-case, that
would definitely be material for an auxiliary function instead of a
view column.)

regards, tom lane