Horton

Re: [BUG]Update Toast data failure in logical replication

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Euler Taveira <euler@eulerto.com>, Michael Paquier <michael@paquier.xyz>, Petr Jelinek <petr.jelinek@enterprisedb.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Andres Freund <andres@anarazel.de>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-02-10T13:34:17Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. WAL log unchanged toasted replica identity key attributes.

  2. Add new wal_level, logical, sufficient for logical decoding.

  3. Add the notion of REPLICA IDENTITY for a table.

On Mon, Feb 7, 2022 at 1:27 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Mon, Feb 7, 2022 at 12:25 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > Attached please find the modified patches.
>
> I have looked into the latest modification and back branch patches and
> they look fine to me.
>

Today, while looking at this patch again, I think I see one problem
with the below change (referring pg10 patch):
+ if (attrnum < 0)
+ {
+ if (attrnum != ObjectIdAttributeNumber &&
+ attrnum != TableOidAttributeNumber)
+ {
+ modified = bms_add_member(modified,
+   attrnum -
+   FirstLowInvalidHeapAttributeNumber);
+ continue;
+ }
+ }
...
...
+ /* No need to check attributes that can't be stored externally. */
+ if (isnull1 || TupleDescAttr(tupdesc, attrnum - 1)->attlen != -1)
+ continue;

I think it is possible that we use TupleDescAttr for system attribute
(in this case ObjectIdAttributeNumber/TableOidAttributeNumber) which
will be wrong as it contains only user attributes, not system
attributes. See comments atop TupleDescData.

I think this check should be modified to  if (attrnum < 0 || isnull1
|| TupleDescAttr(tupdesc, attrnum - 1)->attlen != -1). What do you
think?

* Another minor comment:
+ if (!heap_attr_equals(RelationGetDescr(relation), attrnum, value1,
+   value2, isnull1, isnull2))

I think here we can directly use tupdesc instead of RelationGetDescr(relation).

-- 
With Regards,
Amit Kapila.