| From: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Rajeev rastogi <rajeev(dot)rastogi(at)huawei(dot)com>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Index scan optimization |
| Date: | 2014-09-22 13:46:55 |
| Message-ID: | 5420284F.90006@vmware.com |
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| Lists: | pgsql-hackers |
On 09/22/2014 04:45 PM, Tom Lane wrote:
> Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> writes:
>> On 09/22/2014 07:47 AM, Rajeev rastogi wrote:
>>> So my proposal is to skip the condition check on the first scan key condition for every tuple.
>
>> The same happens in a single-column case. If you have a query like
>> "SELECT * FROM tbl2 where id2 > 'a'", once you've found the start
>> position of the scan, you know that all the rows that follow match too.
>
> ... unless you're doing a backwards scan.
Sure. And you have to still check for NULLs. Have to get the details right..
- Heikki
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