Re: Table AM Interface Enhancements

On Mon, 8 Apr 2024 at 13:34, Alexander Korotkov <aekorotkov(at)gmail(dot)com>
wrote:

> On Mon, Apr 8, 2024 at 10:18 AM Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com>
> wrote:
> > 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.
>
> Please, check this. Instead of keeping two APIs, it generalizes
> acquire_sample_rows(). The downside is change of
> AcquireSampleRowsFunc signature, which would need some changes in FDWs
> too.
>
To me, both approaches v1-0001-Turn-back... and v2-0001-Generalize... and
patch v2 look good.

Pavel.