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

On Tue, May 26, 2020 at 10:27 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Fri, May 22, 2020 at 6:21 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> > On Mon, May 18, 2020 at 5:57 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > >
> > > Few comments on v20-0010-Bugfix-handling-of-incomplete-toast-tuple
> > > 1.
> > > + /*
> > > + * If this is a toast insert then set the corresponding bit. Otherwise, if
> > > + * we have toast insert bit set and this is insert/update then clear the
> > > + * bit.
> > > + */
> > > + if (toast_insert)
> > > + toptxn->txn_flags |= RBTXN_HAS_TOAST_INSERT;
> > > + else if (rbtxn_has_toast_insert(txn) &&
> > > + ChangeIsInsertOrUpdate(change->action))
> > > + {
> > >
> > > Here, it might better to add a comment on why we expect only
> > > Insert/Update? Also, it might be better that we add an assert for
> > > other operations.
> >
> > I have added comments that why on Insert/Update we clean the flag.
> > But I don't think we only expect insert/update, we might get the
> > toast delete right? because in toast update we will do toast delete +
> > toast insert. So when we get toast delete we just don't want to do
> > anything.
> >
>
> Okay, that makes sense.
>
> > >
> > > 2.
> > > @@ -1865,8 +1920,8 @@ ReorderBufferProcessTXN(ReorderBuffer *rb,
> > > ReorderBufferTXN *txn,
> > > * disk.
> > > */
> > > dlist_delete(&change->node);
> > > - ReorderBufferToastAppendChunk(rb, txn, relation,
> > > - change);
> > > + ReorderBufferToastAppendChunk(rb, txn, relation,
> > > + change);
> > > }
> > >
> > > This seems to be a spurious change.
> >
> > Done
> >
> > 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.

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