On Wed, Jul 14, 2021 at 3:58 PM Tomas Vondra <tomas.von...@enterprisedb.com> wrote: > > On 7/14/21 7:39 AM, Amit Kapila wrote: > > On Wed, Jul 14, 2021 at 6:28 AM Euler Taveira <eu...@eulerto.com> wrote: > >> > >> On Tue, Jul 13, 2021, at 6:06 PM, Alvaro Herrera wrote: > >> > >> 1. if you use REPLICA IDENTITY FULL, then the expressions would work > >> even if they use any other column with DELETE. Maybe it would be > >> reasonable to test for this in the code and raise an error if the > >> expression requires a column that's not part of the replica identity. > >> (But that could be relaxed if the publication does not publish > >> updates/deletes.) > >> > > > > +1. > > > >> I thought about it but came to the conclusion that it doesn't worth it. > >> Even > >> with REPLICA IDENTITY FULL expression evaluates to false if the column > >> allows > >> NULL values. Besides that REPLICA IDENTITY is changed via another DDL > >> (ALTER > >> TABLE) and you have to make sure you don't allow changing REPLICA IDENTITY > >> because some row filter uses the column you want to remove from it. > >> > > > > Yeah, that is required but is it not feasible to do so? > > > >> 2. For UPDATE, does the expression apply to the old tuple or to the new > >> tuple? You say it's the new tuple, but from the user point of view I > >> think it would make more sense that it would apply to the old tuple. > >> (Of course, if you're thinking that the R.I. is the PK and the PK is > >> never changed, then you don't really care which one it is, but I bet > >> that some people would not like that assumption.) > >> > >> New tuple. The main reason is that new tuple is always there for UPDATEs. > >> > > > > I am not sure if that is a very good reason to use a new tuple. > > > > True. Perhaps we should look at other places with similar concept of > WHERE conditions and old/new rows, and try to be consistent with those? > > I can think of: > > 1) updatable views with CHECK option > > 2) row-level security > > 3) triggers > > Is there some reasonable rule which of the old/new tuples (or both) to > use for the WHERE condition? Or maybe it'd be handy to allow referencing > OLD/NEW as in triggers? >
I think apart from the above, it might be good if we can find what some other databases does in this regard? -- With Regards, Amit Kapila.
