Re: Table AM Interface Enhancements

Hi, Alexander and Andres!

On Mon, 8 Apr 2024 at 03:25, Alexander Korotkov <aekorotkov(at)gmail(dot)com>
wrote:

> Hi,
>
> On Mon, Apr 8, 2024 at 12:40 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > On 2024-03-30 23:33:04 +0200, Alexander Korotkov wrote:
> > > I've pushed 0001, 0002 and 0006.
> >
> > I briefly looked at 27bc1772fc81 and I don't think the state post this
> commit
> > makes sense. Before this commit another block based AM could implement
> analyze
> > without much code duplication. Now a large portion of analyze.c has to be
> > copied, because they can't stop acquire_sample_rows() from calling
> > heapam_scan_analyze_next_block().
> >
> > I'm quite certain this will break a few out-of-core AMs in a way that
> can't
> > easily be fixed.
>
> I was under the impression there are not so many out-of-core table
> AMs, which have non-dummy analysis implementations. And even if there
> are some, duplicating acquire_sample_rows() isn't a big deal.
>
> But given your feedback, I'd like to propose to keep both options
> open. Turn back the block-level API for analyze, but let table-AM
> implement its own analyze function. Then existing out-of-core AMs
> wouldn't need to do anything (or probably just set the new API method
> to NULL).
>
I think that providing both new and old interface functions for block-based
and non-block based custom am is an excellent compromise.

The patch v1-0001-Turn-back.. is mainly an undo of part of the 27bc1772fc81
that had turned off _analyze_next_tuple..analyze_next_block for external
callers. If some extensions are already adapted to the old interface
functions, they are free to still use it.

> And even for non-block based AMs, the new interface basically requires
> > reimplementing all of analyze.c.
> .
> Non-lock base AM needs to just provide an alternative implementation
> for what acquire_sample_rows() does. This seems like reasonable
> effort for me, and surely not reimplementing all of analyze.c.
>
I agree.

Regards,
Pavel Borisov
Supabase