Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions

On Tue, May 26, 2020 at 4:46 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Tue, May 26, 2020 at 2:44 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> > On Tue, May 26, 2020 at 10:27 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > > >
> > > > 2. There is a bug fix in handling the stream abort in 0008 (earlier it
> > > > was 0006).
> > > >
> > >
> > > The code changes look fine but it is not clear what was the exact
> > > issue. Can you explain?
> >
> > Basically, in case of an empty subtransaction, we were reading the
> > subxacts info but when we could not find the subxid in the subxacts
> > info we were not releasing the memory. So on next subxact_info_read
> > it will expect that subxacts should be freed but we did not free it in
> > that !found case.
> >
>
> Okay, on looking at it again, the same code exists in
> subxact_info_write as well. It is better to have a function for it.
> Can we have a structure like SubXactContext for all the variables used
> for subxact? As mentioned earlier I find the allocation/deallocation
> of subxacts a bit ad-hoc, so there will always be a chance that we can
> forget to free it. Having it allocated in memory context which we can
> reset later might reduce that risk. One idea could be that we have a
> special memory context for start and stop messages which can be used
> to allocate the subxacts there. In case of commit/abort, we can allow
> subxacts information to be allocated in ApplyMessageContext which is
> reset at the end of each protocol message.

Changed as per this.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com