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

On Mon, Jan 6, 2020 at 4:36 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Mon, Jan 6, 2020 at 3:56 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> >
> > On Mon, Jan 6, 2020 at 2:11 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > > 3.
> > > +static void
> > > +ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
> > > {
> > > ..
> > > + /*
> > > + * If this is a subxact, we need to stream the top-level transaction
> > > + * instead.
> > > + */
> > > + if (txn->toptxn)
> > > + {
> > > +
> > > ReorderBufferStreamTXN(rb, txn->toptxn);
> > > + return;
> > > + }
> > >
> > > Is it ever possible that we reach here for subtransaction, if not,
> > > then it should be Assert rather than if condition?
> >
> > ReorderBufferCheckMemoryLimit, can call it either for the
> > subtransaction or for the main transaction, depends upon in which
> > ReorderBufferTXN you are adding the current change.
> >
>
> That function has code like below:
>
> ReorderBufferCheckMemoryLimit()
> {
> ..
> if (ReorderBufferCanStream(rb))
> {
> /*
> * Pick the largest toplevel transaction and evict it from memory by
> * streaming the already decoded part.
> */
> txn = ReorderBufferLargestTopTXN(rb);
> /* we know there has to be one, because the size is not zero */
> Assert(txn && !txn->toptxn);
> ..
> ReorderBufferStreamTXN(rb, txn);
> ..
> }
>
> How can it ReorderBufferTXN pass for subtransaction?
>
Hmm, I missed it. You are right, will fix it.

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