| From: | Robert Klemme <shortcutter(at)googlemail(dot)com> |
|---|---|
| To: | Li Jin <ljin(at)tripadvisor(dot)com> |
| Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Performance penalty when using WITH |
| Date: | 2011-08-03 17:13:23 |
| Message-ID: | CAM9pMnMx6aG-XQFvQSUTa-jWBbeEC23nS6iH7_qGiGpymc_xmA@mail.gmail.com |
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| Lists: | pgsql-performance |
On Wed, Aug 3, 2011 at 3:27 PM, Li Jin <ljin(at)tripadvisor(dot)com> wrote:
> Robert，
> I've built an index on this expression firstname || ' ' ||
> substring(lastname,1,1). I believe this is the best index for this
> particular query. Correct me if I am wrong.
Maybe, maybe not. Difficult to tell from a distance. I would have an
index on (firstname, lastname). You could try that and look at the
plan for the other query. That's the only ultimate test which will
give you hard facts.
Kind regards
robert
--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/
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