Horton

Re: Added schema level support for publication.

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: vignesh C <vignesh21@gmail.com>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>, Peter Smith <smithpb2250@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Greg Nancarrow <gregn4422@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Rahila Syed <rahilasyed90@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: 2021-09-20T10:27:35Z
Lists: pgsql-hackers 
On Fri, Sep 17, 2021 at 5:40 PM vignesh C <vignesh21@gmail.com> wrote:
>
> On Thu, Sep 16, 2021 at 9:54 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > I think there is one more similar locking problem.
> > AlterPublicationSchemas()
> > {
> > ..
> > + if (stmt->action == DEFELEM_ADD)
> > + {
> > + List *rels;
> > +
> > + rels = GetPublicationRelations(pubform->oid, PUBLICATION_PART_ROOT);
> > + RelSchemaIsMemberOfSchemaList(rels, schemaidlist, true);
> > ...
> > ...
> > }
> >
> > Here, we don't have a lock on the relation. So, what if the relation
> > is concurrently dropped after you get the rel list by
> > GetPublicationRelations?
>
> This works fine without locking even after concurrent drop, I felt
> this works because of MVCC.
>

Can you share the exact scenario you have tested? I think here it can
give a wrong error because it might access invalid cache entry, so I
think a lock is required here. Also, as said before, this might help
to make the rel list consistent in function
CheckObjSchemaNotAlreadyInPublication().

-- 
With Regards,
Amit Kapila.

Commits

  1. Include schema/table publications even with exclude options in dump.

  2. Rename some enums to use TABLE instead of REL.

  3. Add tap tests for the schema publications.

  4. Allow publishing the tables of schema.

  5. In pg_dump, use simplehash.h to look up dumpable objects by OID.