Re: Transaction commits VS Transaction commits (with parallel) VSquery mean time - Mailing list pgsql-hackers

From Amit Kapila
Subject Re: Transaction commits VS Transaction commits (with parallel) VSquery mean time
Date
Msg-id CAA4eK1Lt8zKaN9ehUZLFkiCYYkMi9FCv53n6BwKKumEQ_5cekg@mail.gmail.com
Whole thread Raw
In response to Re: Transaction commits VS Transaction commits (with parallel) VSquery mean time  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Responses Re: Transaction commits VS Transaction commits (with parallel) VSquery mean time
List pgsql-hackers
On Sat, Mar 23, 2019 at 9:50 AM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
>
> On 2019-Mar-23, Amit Kapila wrote:
>
> > I think some users might also be interested in the write transactions
> > happened in the system, basically, those have consumed xid.
>
> Well, do they really want to *count* these transactions, or is it enough
> to keep an eye on the "age" of some XID column?  Other than for XID
> freezing purposes, I don't see such internal transactions as very
> interesting.
>

That's what I also had in mind.  I think doing anything more than just
fixing the count for the parallel cooperating transaction by parallel
workers doesn't seem intuitive to me. I mean if we want we can commit
the fix such that all supporting transactions by parallel worker
shouldn't be counted, but I am not able to convince myself that that
is the good fix.  Instead, I think rather than fixing that one case we
should think more broadly about all the supportive transactions
happening in the various operations.  Also, as that is a kind of
behavior change, we should discuss that as a separate topic.

I know what I am proposing here won't completely fix the problem Hari
is facing, but I am not sure what else we can do here which doesn't
create some form of inconsistency with other parts of the system.


--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com


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