| From: | Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com> |
|---|---|
| To: | Floris Van Nee <florisvannee(at)Optiver(dot)com>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
| Cc: | Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Alexander Kuzmenkov <a(dot)kuzmenkov(at)postgrespro(dot)ru>, Peter Geoghegan <pg(at)bowt(dot)ie>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Bhushan Uparkar <bhushan(dot)uparkar(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, James Coleman <jtc331(at)gmail(dot)com> |
| Subject: | Re: Index Skip Scan |
| Date: | 2019-06-13 16:31:54 |
| Message-ID: | 4d469bf2-49ff-bc3d-a428-6c7b5d87d526@redhat.com |
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| Lists: | pgsql-hackers |
Hi,
On 6/5/19 3:39 PM, Floris Van Nee wrote:
> Thanks! I've verified that it works now.
Here is a rebased version.
> I was wondering if we're not too strict in some cases now though. Consider the following queries:
[snip]
> This is basically the opposite case - when distinct_pathkeys matches the filtered list of index keys, an index skip scan could be considered. Currently, the user needs to write 'distinct m,f' explicitly, even though he specifies in the WHERE-clause that 'm' can only have one value anyway. Perhaps it's fine like this, but it could be a small improvement for consistency.
>
I think it would be good to get more feedback on the patch in general
before looking at further optimizations. We should of course fix any
bugs that shows up.
Thanks for your testing and feedback !
Best regards,
Jesper
| Attachment | Content-Type | Size |
|---|---|---|
| v18-0001-Index-skip-scan.patch | text/x-patch | 51.1 KB |
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