On Mon, Jan 25, 2021 at 5:18 PM japin <japi...@hotmail.com> wrote: > > > On Mon, 25 Jan 2021 at 17:18, Bharath Rupireddy > <bharath.rupireddyforpostg...@gmail.com> wrote: > > On Mon, Jan 25, 2021 at 2:42 PM Dilip Kumar <dilipbal...@gmail.com> wrote: > >> > >> On Mon, Jan 25, 2021 at 1:10 PM vignesh C <vignes...@gmail.com> wrote: > >> > > >> > On Thu, Jan 21, 2021 at 10:21 PM Bharath Rupireddy > >> > <bharath.rupireddyforpostg...@gmail.com> wrote: > >> > > > >> > > On Thu, Jan 21, 2021 at 6:56 PM vignesh C <vignes...@gmail.com> wrote: > >> > > > > >> > > > Hi, > >> > > > > >> > > > Creating/altering subscription is successful when we specify a > >> > > > publication which does not exist in the publisher. I felt we should > >> > > > throw an error in this case, that will help the user to check if > >> > > > there > >> > > > is any typo in the create subscription command or to create the > >> > > > publication before the subscription is created. > >> > > > If the above analysis looks correct, then please find a patch that > >> > > > checks if the specified publications are present in the publisher and > >> > > > throws an error if any of the publications is missing in the > >> > > > publisher. > >> > > > Thoughts? > >> > > > >> > > I was having similar thoughts (while working on the logical > >> > > replication bug on alter publication...drop table behaviour) on why > >> > > create subscription succeeds without checking the publication > >> > > existence. I checked in documentation, to find if there's a strong > >> > > reason for that, but I couldn't. Maybe it's because of the principle > >> > > "first let users create subscriptions, later the publications can be > >> > > created on the publisher system", similar to this behaviour > >> > > "publications can be created without any tables attached to it > >> > > initially, later they can be added". > >> > > > >> > > Others may have better thoughts. > >> > > > >> > > If we do check publication existence for CREATE SUBSCRIPTION, I think > >> > > we should also do it for ALTER SUBSCRIPTION ... SET PUBLICATION. > >> > > > >> > > I wonder, why isn't dropping a publication from a list of publications > >> > > that are with subscription is not allowed? > >> > > > >> > > Some comments so far on the patch: > >> > > > >> > > 1) I see most of the code in the new function check_publications() and > >> > > existing fetch_table_list() is the same. Can we have a generic > >> > > function, with maybe a flag to separate out the logic specific for > >> > > checking publication and fetching table list from the publisher. > >> > > >> > I have made the common code between the check_publications and > >> > fetch_table_list into a common function > >> > get_appended_publications_query. I felt the rest of the code is better > >> > off kept as it is. > >> > The Attached patch has the changes for the same and also the change to > >> > check publication exists during alter subscription set publication. > >> > Thoughts? > >> > > >> > >> So basically, the create subscription will throw an error if the > >> publication does not exist. So will you throw an error if we try to > >> drop the publication which is subscribed by some subscription? I mean > >> basically, you are creating a dependency that if you are creating a > >> subscription then there must be a publication that is not completely > >> insane but then we will have to disallow dropping the publication as > >> well. Am I missing something? > > > > Do you mean DROP PUBLICATION non_existent_publication;? > > > > Or > > > > Do you mean when we drop publications from a subscription? If yes, do > > we have a way to drop a publication from the subscription? See below > > one of my earlier questions on this. > > "I wonder, why isn't dropping a publication from a list of > > publications that are with subscription is not allowed?" > > At least, I see no ALTER SUBSCRIPTION ... DROP PUBLICATION mypub1 or > > something similar? > > > > Why we do not support ALTER SUBSCRIPTION...ADD/DROP PUBLICATION? When we > have multiple publications in subscription, but I want to add/drop a single > publication, it is conveient. The ALTER SUBSCRIPTION...SET PUBLICATION... > should supply the completely publications. > > Sorry, this question is unrelated with this subject.
Please start a new thread for this, let's discuss this separately. Regards, Vignesh EnterpriseDB: http://www.enterprisedb.com
