Re: row filtering for logical replication

On Mon, Jan 24, 2022 at 1:19 PM Greg Nancarrow <gregn4422(at)gmail(dot)com> wrote:
>
> On Mon, Jan 24, 2022 at 5:09 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > But that is not what I am seeing in Logs with a test case where the
> > row filter column has NULL values. Could you please try that see what
> > is printed in LOG?
> >
> > You can change the code to make the elevel as LOG to get the results
> > easily. The test case I tried is as follows:
> > Node-1:
> > postgres=# create table t1(c1 int, c2 int);
> > CREATE TABLE
> > postgres=# create publication pub for table t1 WHERE (c1 > 10);
> > CREATE PUBLICATION
> >
> > Node-2:
> > postgres=# create table t1(c1 int, c2 int);
> > CREATE TABLE
> > postgres=# create subscription sub connection 'dbname=postgres' publication pub;
> > NOTICE: created replication slot "sub" on publisher
> > CREATE SUBSCRIPTION
> >
> > After this on publisher-node, I see the LOG as "LOG: row filter
> > evaluates to false (isnull: true)". I have verified that in the code
> > as well (in slot_deform_heap_tuple), we set the value as 0 for isnull
> > which matches above observation.
> >
>
> There are obviously multiple code paths under which a column can end up as NULL.
> Doing one NULL-column test case, and finding here that
> "DatumGetBool(ret)" is "false" when "isnull" is true, doesn't prove it
> will be like that for ALL possible cases.
>

Sure, I just wanted to see the particular test which leads to failure
so that I or others can know (or debug) why in some cases it behaves
differently. Anyway, for others, the below test can show the results:

CREATE TABLE tab_rowfilter_1 (a int primary key, b text);
alter table tab_rowfilter_1 replica identity full ;
INSERT INTO tab_rowfilter_1 (a, b) VALUES (1600, 'test 1600');
CREATE PUBLICATION pub FOR TABLE tab_rowfilter_1 WHERE (a > 1000 AND b
<> 'filtered');

UPDATE tab_rowfilter_1 SET b = NULL WHERE a = 1600;

So, we can change this DEBUG log.

--
With Regards,
Amit Kapila.