Re: Use streaming read API in ANALYZE

On Tue, Sep 10, 2024 at 10:27 AM Thomas Munro <thomas(dot)munro(at)gmail(dot)com> wrote:
> Mats, what do you think about
> this? (I haven't tried to preserve the prefetching behaviour, which
> probably didn't actually too work for you in v16 anyway at a guess,
> I'm just looking for the absolute simplest thing we can do to resolve
> this API mismatch.) TimeScale could then continue to use its v16
> coding to handle the two-relations-in-a-trenchcoat problem, and we
> could continue discussing how to make v18 better.

. o O { Spitballing here: if we add that tiny function I showed to get
you unstuck for v17, then later in v18, if we add a multi-relation
ReadStream constructor/callback (I have a patch somewhere, I want to
propose that as it is needed for streaming recovery), you could
construct a new ReadSteam of your own that is daisy-chained from that
one. You could keep using your N + M block numbering scheme if you
want to, and the callback of the new stream could decode the block
numbers and redirect to the appropriate relation + real block number.
That way you'd get I/O concurrency for both relations (for now just
read-ahead advice, but see Andres's AIO v2 thread). That'd
essentially be a more supported version of the 'access the struct
internals' idea (or at least my understanding of what you had in
mind), through daisy-chained streams. A little weird maybe, and maybe
the redesign work will result in something completely
different/better... just a thought... }