Re: Bitmapsets as Nodes

On Mon, Oct 17, 2022 at 6:30 PM Amit Langote <amitlangote09(at)gmail(dot)com> wrote:
> For a couple of patches that I am working on ([1], [2]), I have needed
> to put Bitmapsets into a List that is in turn part of a Plan tree or a
> Node tree that may be written (using outNode) and read (using
> nodeRead). Bitmapsets not being a Node themselves causes the
> write/read of such Plan/Node trees (containing Bitmapsets in a List)
> to not work properly.
>
> So, I included a patch in both of those threads to add minimal support
> for Bitmapsets to be added into a Plan/Node tree without facing the
> aforementioned problem, though Peter E suggested [3] that it would be
> a good idea to discuss it more generally in a separate thread, so this
> email. Attached a patch to make the infrastructure changes necessary
> to allow adding Bitmapsets as Nodes, though I have not changed any of
> the existing Bitmapset that are added either to Query or to
> PlannedStmt to use that infrastructure. That is, by setting their
> NodeTag and changing gen_node_support.pl to emit
> WRITE/READ_NODE_FIELD() instead of WRITE/READ_BITMAPSET_FIELD() for
> any Bitmapsets encountered in a Node tree. One thing I am not quite
> sure about is who would be setting the NodeTag, the existing routines
> in bitmapset.c, or if we should add wrappers that do.
>
> Actually, Tom had posted about exactly the same thing last year [4],
> though trying to make Bitmapset Nodes became unnecessary after he
> resolved the problem that required making Bitmapsets Nodes by other
> means -- by getting rid of the field that was a List of Bitmapset
> altogether. Maybe I should try to do the same in the case of both [1]
> and [2]? In fact, I have tried getting rid of the need for List of
> Bitmapset for [1], and I like the alternative better in that case, but
> for [2], it still seems that a List of Bitmapset may be better than
> List of some-new-Node-containing-the-Bitmapset.

FTR, this has been taken care of in 5e1f3b9ebf6e5.

--
Thanks, Amit Langote
EDB: http://www.enterprisedb.com