Re: Index Skip Scan

> On 18 June 2018 at 19:31, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> wrote:
>>
>> A couple of questions to begin with.
>>
>> Should the patch continue to "piggy-back" on T_IndexOnlyScan, or should
>> a new node (T_IndexSkipScan) be created ? If latter, then there likely
>> will be functionality that needs to be refactored into shared code
>> between the nodes.
>
> Is skip scan only possible for index-only scan? I guess, that no. We
> could also make plain index scan to behave like a skip scan. And it
> should be useful for accelerating DISTINCT ON clause. Thus, we might
> have 4 kinds of index scan: IndexScan, IndexOnlyScan, IndexSkipScan,
> IndexOnlySkipScan. So, I don't think I like index scan nodes to
> multiply this way, and it would be probably better to keep number
> nodes smaller. But I don't insist on that, and I would like to hear
> other opinions too.

In one of patches I'm working on I had similar situation, when I wanted to
split one node into two similar nodes (before I just extended it) and logically
it made perfect sense. But it turned out to be quite useless and the advantage
I've got wasn't worth it - and just to mention, those nodes had more differences
than in this patch. So I agree that probably it would be better to keep using
IndexOnlyScan.

> On 19 June 2018 at 03:40, Michael Paquier <michael(at)paquier(dot)xyz> wrote:
> On Tue, Jun 19, 2018 at 12:06:59AM +0300, Alexander Korotkov wrote:
>> Assuming this, should we have possibility to register patch to
>> September CF from now?
>
> There cannot be two commit fests marked as open at the same time as
> Magnus mentions here:
> https://www.postgresql.org/message-id/CABUevEx1k+axZcV2t3wEYf5uLg72YbKSch_hUhFnZq+-KSoJsA@mail.gmail.com
>
> In this case, could you wait that the next CF is marked as in progress and
> that the one of September is opened?

Yep, since the next CF will start shortly that's the easiest thing to do.