| From: | Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
|---|---|
| To: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
| Cc: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Floris Van Nee <florisvannee(at)optiver(dot)com>, James Coleman <jtc331(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Rafia Sabih <rafia(dot)pghackers(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, "bhushan(dot)uparkar(at)gmail(dot)com" <bhushan(dot)uparkar(at)gmail(dot)com> |
| Subject: | Re: Index Skip Scan |
| Date: | 2020-05-16 04:25:42 |
| Message-ID: | CAFiTN-sEfZYugCQ9_1EM9qZTePpSZ3SfGztd4qkXGu0_B4MfqQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, 15 May 2020 at 6:06 PM, Dmitry Dolgov <9erthalion6(at)gmail(dot)com> wrote:
> > On Wed, May 13, 2020 at 02:37:21PM +0530, Dilip Kumar wrote:
> >
> > + if (_bt_scankey_within_page(scan, so->skipScanKey, so->currPos.buf,
> dir))
> > + {
> >
> > Here we expect whether the "next" unique key can be found on this page
> > or not, but we are using the function which suggested whether the
> > "current" key can be found on this page or not. I think in boundary
> > cases where the high key is equal to the current key, this function
> > will return true (which is expected from this function), and based on
> > that we will simply scan the current page and IMHO that cost could be
> > avoided no?
>
> Yes, looks like you're right, there is indeed an unecessary extra scan
> happening. To avoid that we can see the key->nextkey and adjust higher
> boundary correspondingly. Will also add this into the next rebased
> patch, thanks!
Great thanks!
> --
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com
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