Re: [PoC] Improve dead tuple storage for lazy vacuum

On Mon, Nov 14, 2022 at 10:00 PM John Naylor
<john(dot)naylor(at)enterprisedb(dot)com> wrote:
>
> On Mon, Nov 14, 2022 at 3:44 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > 0004 patch is a new patch supporting a pointer tagging of the node
> > kind. Also, it introduces rt_node_ptr we discussed so that internal
> > functions use it rather than having two arguments for encoded and
> > decoded pointers. With this intermediate patch, the DSA support patch
> > became more readable and understandable. Probably we can make it
> > smaller further if we move the change of separating the control object
> > from radix_tree to the main patch (0002). The patch still needs to be
> > polished but I'd like to check if this idea is worthwhile. If we agree
> > on this direction, this patch will be merged into the main radix tree
> > implementation patch.
>
> Thanks for the new patch set. I've taken a very brief look at 0004 and I think the broad outlines are okay. As you say it needs polish, but before going further, I'd like to do some experiments of my own as I mentioned earlier:
>
> - See how much performance we actually gain from tagging the node kind.
> - Try additional size classes while keeping the node kinds to only four.
> - Optimize node128 insert.
> - Try templating out the differences between local and shared memory. With local memory, the node-pointer struct would be a union, for example. Templating would also reduce branches and re-simplify some internal APIs, but it's likely that would also make the TID store and/or vacuum more complex, because at least some external functions would be duplicated.

Thanks! Please let me know if there is something I can help with.

In the meanwhile, I'd like to make some progress on the vacuum
integration and improving the test coverages.

Regards,

--
Masahiko Sawada
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