Re: Table AM Interface Enhancements

Hi, Alexander

On Mon, 8 Apr 2024 at 13:59, Pavel Borisov <pashkin(dot)elfe(at)gmail(dot)com> wrote:

>
>
> 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.
>

I added some changes in comments to better reflect changes in patch v2. See
a patch v3 (code unchanged from v2)

Regards,
Pavel