Re: row filtering for logical replication

On Wed, Aug 25, 2021 at 10:57 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Wed, Aug 25, 2021 at 5:52 AM Euler Taveira <euler(at)eulerto(dot)com> wrote:
> >
> > On Tue, Aug 24, 2021, at 4:46 AM, Peter Smith wrote:

> >
> > Anyway, I have implemented the suggested cache change because I agree
> > it is probably theoretically superior, even if in practice there is
> > almost no difference.
> >
> > I didn't inspect your patch carefully but it seems you add another List to
> > control this new cache mechanism. I don't like it. IMO if we can use the data
> > structures that we have now, let's implement your idea; otherwise, -1 for this
> > new micro optimization.
> >
>
> As mentioned above, without this we will invalidate many cached
> expressions even though it is not required. I don't deny that there
> might be a better way to achieve the same and if you or Peter have any
> ideas, I am all ears.
>

I see that the new list is added to store row_filter node which we
later use to compute expression. This is not required for invalidation
but for delaying the expression evaluation till it is required (for
example, for truncate, we may not need the row evaluation, so there is
no need to compute it). Can we try to postpone the syscache lookup to
a later stage when we are actually doing row_filtering? If we can do
that, then I think we can avoid having this extra list?

--
With Regards,
Amit Kapila.