| From: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
|---|---|
| To: | Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Alexander Kuzmenkov <a(dot)kuzmenkov(at)postgrespro(dot)ru> |
| Cc: | Peter Geoghegan <pg(at)bowt(dot)ie>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Bhushan Uparkar <bhushan(dot)uparkar(at)gmail(dot)com>, PostgreSQL Hackers <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: | 2019-01-26 17:45:54 |
| Message-ID: | CA+q6zcVFc3+Wm_EfsEif5oy9HKxA+wm9Z2iPSzecSCBKANg5Mw@mail.gmail.com |
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| Lists: | pgsql-hackers |
> On Thu, Dec 20, 2018 at 2:46 PM Dmitry Dolgov <9erthalion6(at)gmail(dot)com> wrote:
>
> I've performed some testing, and on my environment with a dataset of 10^7
> records:
>
> * everything below 7.5 * 10^5 unique records out of 10^7 was faster with skip
> scan.
>
> * above 7.5 * 10^5 unique records skip scan was slower, e.g. for 10^6 unique
> records it was about 20% slower than the regular index scan.
>
> For me these numbers sound good, since even in quite extreme case of
> approximately 10 records per group the performance of index skip scan is close
> to the same for the regular index only scan.
Rebased version after rd_amroutine was renamed.
| Attachment | Content-Type | Size |
|---|---|---|
| 0001-Index-skip-scan-v6.patch | application/octet-stream | 44.8 KB |
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