Re: [WIP]Vertical Clustered Index (columnar store extension) - take2

On Fri, May 23, 2025 at 4:29 PM Tomas Vondra <tomas(at)vondra(dot)me> wrote:

> Also, Alvaro seemed to think TAM is the way to go, and in order to keep
> the OLTP performance he suggested to use both heap and VCI at the same
> time, in different "forks". I'm not sure how would that work, or if we
> can already do that - AFAIK we can't, because ForkNumber does not allow
> adding custom forks. We'd have to relax that, or invent some sort of
> federated TAM (that just multiplexes it to two TAMs). Maybe.
>
> But it's not like the IAM approach doesn't need to do this. The first
> patch had to add stuff to a lot of random places to make this work. And
> some of the places touch stuff that we don't expect indexes to worry
> about, like ALTER TABLE, etc.

I suspect another option would be to handle this with table inheritance:
have one child that is heap-based, a second that's VCI, and a background
job to move data from heap to VCI (and vice-versa for updates and maybe
deletes).

Note that you could actually implement all that in user-space. Personally
I'd much rather have a way to do pure VCI / column-store sooner and manage
it myself than have to wait another release (or more) to get a complete
solution...