Re: POC, WIP: OR-clause support for indexes

Hi! Thanks for your contribution to this topic!

On 17.07.2024 03:03, Alexander Korotkov wrote:
> Hi, Alena!
>
> On Thu, Jul 11, 2024 at 7:17 PM Alena Rybakina
> <a(dot)rybakina(at)postgrespro(dot)ru> wrote:
>> I have finished patch and processed almost your suggestions (from [0], [1], [2]). It remains only to add tests where the conversion should work, but I will add this in the next version.
>>
>> [0] https://www.postgresql.org/message-id/3381819.e9J7NaK4W3%40thinkpad-pgpro
>>
>> [1] https://www.postgresql.org/message-id/9736220.CDJkKcVGEf%40thinkpad-pgpro
>>
>> [2] https://www.postgresql.org/message-id/2193851.QkHrqEjB74%40thinkpad-pgpro
> I dare making another revision of this patch. In this version I moved
> the transformation to match_clause_to_indexcol(). Therefore, this
> allows to successfully construct index scans with SAOP, but has no
> degradation in generation of bitmap scans which I observed in [1] and
> [2]. BTW, I found that my description in [2] lacks of t_b_c_idx index
> definition. Sorry for that.
>
> Given that now we're doing OR-to-ANY transformation solely to match an
> index we don't need complex analysis of OR-list, which potentially
> could take quadratic time. Instead, we're trying to match every OR
> element to an index and quit immediately on failure.

Yes I see that. I will look at this in detail, but so far I have not
found any unpleasant side effects indicating that the patch should be
moved to another place and this is very good)

The only thing that worries me so far is that most likely we will need
to analyze the changes in rinfo and distribute them to others places
where links about them are used.
But I need to look at this in more detail separately before discussing it.

Yes, I am ready to agree that there was no degradation in tests [1] and
[2]. But just in case, I will do a review to rule out any other problems.
> I'd like to head a feedback on the new place to apply the
> transformation. It looks like significant simplification for me and
> the way to go.
>
> Also, I have addressed some of notes by Robert Haas [3]. In v27 we
> don't use expression evaluation, but directly construct an array
> constant when possible. Also we don't transform operator id to string
> and back, but directly construct SAOP instead.
>
> Links.
> 1. https://www.postgresql.org/message-id/CAPpHfduJtO0s9E%3DSHUTzrCD88BH0eik0UNog1_q3XBF2wLmH6g%40mail.gmail.com
> 2. https://www.postgresql.org/message-id/CAPpHfdtSXxhdv3mLOLjEewGeXJ%2BFtfhjqodn1WWuq5JLsKx48g%40mail.gmail.com
> 3. https://www.postgresql.org/message-id/CA%2BTgmobu0DUFCTF28DuAi975mEc4xYqX3xyt8RA0WbnyrYg%2BFw%40mail.gmail.com

Thanks for your effort and any help is welcome)

Yesterday I finished a big project in my work and now I'm ready to
continue working on this thread. I'll write the results one of these days.

--
Regards,
Alena Rybakina
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company