Re: row filtering for logical replication

On Thu, Nov 18, 2021 at 4:32 PM Peter Smith <smithpb2250@gmail.com> wrote:
>
> On Mon, Nov 15, 2021 at 9:31 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Wed, Nov 10, 2021 at 12:36 PM Peter Smith <smithpb2250@gmail.com> wrote:
> > >
> > > On Mon, Nov 8, 2021 at 5:53 PM houzj.fnst@fujitsu.com
> > > <houzj.fnst@fujitsu.com> wrote:
> > > >
> > > > 3) v37-0005
> > > >
> > > > - no parse nodes of any kind other than Var, OpExpr, Const, BoolExpr, FuncExpr
> > > >
> > > > I think there could be other node type which can also be considered as simple
> > > > expression, for exmaple T_NullIfExpr.
> > >
> > > The current walker restrictions are from a previously agreed decision
> > > by Amit/Tomas [1] and from an earlier suggestion from Andres [2] to
> > > keep everything very simple for a first version.
> > >
> > > Yes, you are right, there might be some additional node types that
> > > might be fine, but at this time I don't want to add anything different
> > > without getting their approval to do so. Anyway, additions like this
> > > are all candidates for a future version of this row-filter feature.
> > >
> >
> > I think we can consider T_NullIfExpr unless you see any problem with the same.
>
> Added in v40 [1]
>

I've noticed that row-filters that are testing NULL cannot pass the
current expression validation restrictions.

e.g.1
test_pub=# create publication ptest for table t1 where (a is null);
ERROR:  invalid publication WHERE expression for relation "t1"
HINT:  only simple expressions using columns, constants and immutable
system functions are allowed

e.g.2
test_pub=# create publication ptest for table t1 where (a is not null);
ERROR:  invalid publication WHERE expression for relation "t1"
HINT:  only simple expressions using columns, constants and immutable
system functions are allowed

So I think it would be useful to permit the NullTest also. Is it OK?

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KInd Regards,
Peter Smith.
Fujitsu Australia