Re: Logical Replication - behavior of ALTER PUBLICATION .. DROP TABLE and ALTER SUBSCRIPTION .. REFRESH PUBLICATION

> On Jan 14, 2021, at 8:44 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> 
> On Thu, Jan 14, 2021 at 6:02 PM japin <japinli@hotmail.com> wrote:
>> 
>> On Thu, 14 Jan 2021 at 20:19, Bharath Rupireddy wrote:
>>> On Thu, Jan 14, 2021 at 5:36 PM Li Japin <japinli@hotmail.com> wrote
>>>> Do we really need to access PUBLICATIONRELMAP in this patch? What if
>>>> we just set it to false in the else condition of (if (publish &&
>>>> (relkind != RELKIND_PARTITIONED_TABLE || pub->pubviaroot)))
>>>> 
>>>> Thank for you review. I agree with you, it doesn’t need to access PUBLICATIONRELMAP, since
>>>> We already get the publication oid in GetRelationPublications(relid) [1], which also access
>>>> PUBLICATIONRELMAP.  If the current pub->oid does not in pubids, the publish is false, so we
>>>> do not need publish the table.
>>> 
>>> +1. This is enough.
>>> 
>>>> I have another question, the data->publications is a list, when did it has more then one items?
>>> 
>>> IIUC, when the single table is associated with multiple publications,
>>> then data->publications will have multiple entries. Though I have not
>>> tried, we can try having two or three publications for the same table
>>> and verify that.
>>> 
>> 
>> I try add one table into two publications, but the data->publications has only
>> one item.  Is there something I missed?
>> 
> 
> I think you will have multiple publications in that list when the
> subscriber has subscribed to multiple publications. For example,
> Create Subscription ... Publication pub1, Publication pub2.
> 

Thanks, you are right! When we create a subscription with multiple publications,
the data->publications has more then one items.

-- 
Regrads,
Japin Li.
ChengDu WenWu Information Technology Co.,Ltd.