Re: row filtering for logical replication

On Fri, Jan 7, 2022 at 12:05 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Fri, Jan 7, 2022 at 9:44 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > On Thu, Jan 6, 2022 at 6:42 PM Euler Taveira <euler(at)eulerto(dot)com> wrote:
> > >
> > > IMO we shouldn't reuse ReorderBufferChangeType. For a long-term solution, it is
> > > fragile. ReorderBufferChangeType has values that do not matter for row filter
> > > and it relies on the fact that REORDER_BUFFER_CHANGE_INSERT,
> > > REORDER_BUFFER_CHANGE_UPDATE and REORDER_BUFFER_CHANGE_DELETE are the first 3
> > > values from the enum, otherwise, it breaks rfnodes and no_filters in
> > > pgoutput_row_filter().
> > >
> >
> > I think you mean to say it will break in pgoutput_row_filter_init(). I
> > see your point but OTOH, if we do what you are suggesting then don't
> > we need an additional mapping between ReorderBufferChangeType and
> > RowFilterPublishAction as row filter and pgoutput_change API need to
> > use those values.
> >
>
> Can't we use 0,1,2 as indexes for rfnodes/no_filters based on change
> type as they are local variables as that will avoid the fragileness
> you are worried about. I am slightly hesitant to introduce new enum
> when we are already using reorder buffer change type in pgoutput.c.
>

Euler, I have one more question about this patch for you. I see that
in the patch we are calling coerce_to_target_type() in
pgoutput_row_filter_init_expr() but do we really need the same? We
already do that via
transformPubWhereClauses->transformWhereClause->coerce_to_boolean
before storing where clause expression. It is not clear to me why that
is required? We might want to add a comment if that is required.

--
With Regards,
Amit Kapila.