Re: Index scan optimization

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
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 13:45:14
Message-ID: 12535.1411393514@sss.pgh.pa.us
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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.

regards, tom lane

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