Re: use `proc->pgxactoff` as the value of `index` in `ProcArrayRemove()`

On 5/6/21 3:27 PM, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
>> On 2021-05-07 00:30:13 +0800, 盏一 wrote:
>>> Since we have introduced `pgxactoff` in [941697c3c1ae5d6ee153065adb96e1e63ee11224](https://github.com/postgres/postgres/commit/941697c3c1ae5d6ee153065adb96e1e63ee11224), and `pgxactoff` is always the index of `proc->pgprocno` in `procArray->pgprocnos`. So it seems that we could directly use `proc->pgxactoff` as the value of `index` in `ProcArrayRemove()`? My thought is to replace
>> Sounds like a plan! Do you want to write a patch?
>> If you do, I think it might be worthwhile to add an only-with-assertions
>> loop checking that there's no other entry with the same pgprocno in the
>> dense arrays.
> Hmm, I can definitely see keeping a check that the selected entry
> has the right PID and/or pgprocno, but making it search for duplicates
> seems a bit over the top. The existing code isn't guarding against
> that, and I don't really see a reason why there's a meaningful risk
> of it.
>
>> Given that the code is new in 14, I wonder if we should cram this
>> simplification in before beta?
> +1, seems like a pretty clear missed opportunity in 941697c3c.
>
>

open item then?

cheers

andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com