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

On Mon, Jul 20, 2020 at 4:41 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Mon, Jul 20, 2020 at 2:15 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Mon, Jul 20, 2020 at 12:01 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > >
> > > On Thu, Jul 16, 2020 at 4:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > > >
> > > > On Thu, Jul 16, 2020 at 12:23 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > > > >
> > > > > On Wed, Jul 15, 2020 at 6:59 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> > > > > >
> > > > > >
> > > > > > Let me know what you think of the changes?
> > > > >
> > > > > I have reviewed the changes and looks fine to me.
> > > > >
> > > >
> > > > Thanks, I am planning to start committing a few of the infrastructure
> > > > patches (especially first two) by early next week as we have resolved
> > > > all the open issues and done an extensive review of the entire
> > > > patch-set.  In the attached version, there is a slight change in one
> > > > of the commit messages as compared to the previous version.  I would
> > > > like to describe in brief the first two patches for the sake of
> > > > convenience.  Let me know if you or anyone else sees any problems with
> > > > these.
> > > >
> > > > The first patch in the series allows us to WAL-log subtransaction and
> > > > top-level XID association.  The logical decoding infrastructure needs
> > > > to know which top-level
> > > > transaction the subxact belongs to, in order to decode all the
> > > > changes. Until now that might be delayed until commit, due to the
> > > > caching (GPROC_MAX_CACHED_SUBXIDS), preventing features requiring
> > > > incremental decoding.  So we also write the assignment info into WAL
> > > > immediately, as part of the next WAL record (to minimize overhead)
> > > > only when *wal_level=logical*.  We can not remove the existing
> > > > XLOG_XACT_ASSIGNMENT WAL as that is required for avoiding overflow in
> > > > the hot standby snapshot.
> > > >
> >
> > Pushed, this patch.
> >
> > > >
> > >
> > > The patch set required to rebase after committing the binary format
> > > option support in the create subscription command.  I have rebased the
> > > patch set on the latest head and also added a test case to test
> > > streaming in binary format.
> > >
> >
> > While going through commit 9de77b5453, I noticed below change:
> >
> > @@ -424,6 +424,10 @@ libpqrcv_startstreaming(WalReceiverConn *conn,
> >         PQfreemem(pubnames_literal);
> >         pfree(pubnames_str);
> >
> > +       if (options->proto.logical.binary &&
> > +           PQserverVersion(conn->streamConn) >= 140000)
> > +           appendStringInfoString(&cmd, ", binary 'true'");
> > +
> >
> > Now, the similar change in this patch series is as below:
> >
> > @@ -408,6 +408,9 @@ libpqrcv_startstreaming(WalReceiverConn *conn,
> >   appendStringInfo(&cmd, "proto_version '%u'",
> >   options->proto.logical.proto_version);
> >
> > + if (options->proto.logical.streaming)
> > + appendStringInfo(&cmd, ", streaming 'on'");
> > +
> >
> > I think we also need a version check similar to commit 9de77b5453 to
> > ensure that we send the new option only when connected to a newer
> > version (>=14) primary server.
>
> I have changed that in the attached patch.

There was one warning in release mode in the last version in 0004 so
attaching a new version.

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