Re: Index scan optimization

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От Heikki Linnakangas
Тема Re: Index scan optimization
Дата
Msg-id 5420284F.90006@vmware.com
обсуждение исходный текст
Ответ на Re: Index scan optimization  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Index scan optimization  (Rajeev rastogi <rajeev.rastogi@huawei.com>)
Re: Index scan optimization  (Simon Riggs <simon@2ndquadrant.com>)
Список pgsql-hackers
On 09/22/2014 04:45 PM, Tom Lane wrote:
> Heikki Linnakangas <hlinnakangas@vmware.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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