Re: Gsoc2012 idea, tablesample

Huang Qi Victor

Computer Science of National University of Singapore

> Date: Tue, 17 Apr 2012 09:16:29 +0300
> From: heikki.linnakangas@enterprisedb.com
> To: josh@agliodbs.com
> CC: huangqiyx@hotmail.com; pgsql-hackers@postgresql.org; andres@anarazel.de; alvherre@commandprompt.com; neil.conway@gmail.com; daniel@heroku.com; cbbrowne@gmail.com; kevin.grittner@wicourts.gov
> Subject: [HACKERS] Gsoc2012 idea, tablesample
>
> On 24.03.2012 22:12, Joshua Berkus wrote:
> > Qi,
> >
> > Yeah, I can see that. That's a sign that you had a good idea for a project, actually: your idea is interesting enough that people want to debate it. Make a proposal on Monday and our potential mentors will help you refine the idea.
>
> Yep. The discussion withered, so let me try to summarize:
>
> 1. We probably don't want the SQL syntax to be added to the grammar.
> This should be written as an extension, using custom functions as the
> API, instead of extra SQL syntax.
>
> 2. It's not very useful if it's just a dummy replacement for "WHERE
> random() < ?". It has to be more advanced than that. Quality of the
> sample is important, as is performance. There was also an interesting
> idea of on implementing monetary unit sampling.
>
> I think this would be a useful project if those two points are taken
> care of.
>
> Another idea that Robert Haas suggested was to add support doing a TID
> scan for a query like "WHERE ctid< '(501,1)'". That's not enough work
> for GSoC project on its own, but could certainly be a part of it.
>
> --
> Heikki Linnakangas
> EnterpriseDB http://www.enterprisedb.com
>
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