Gsoc2012 idea, tablesample - Mailing list pgsql-hackers

From Heikki Linnakangas
Subject Gsoc2012 idea, tablesample
Date
Msg-id 4F8D0ABD.4080403@enterprisedb.com
Whole thread Raw
In response to Re: Gsoc2012 Idea --- Social Network database schema  (Joshua Berkus <josh@agliodbs.com>)
Responses Re: Gsoc2012 idea, tablesample  (Qi Huang <huangqiyx@hotmail.com>)
Re: Gsoc2012 idea, tablesample  (Qi Huang <huangqiyx@hotmail.com>)
Re: Gsoc2012 idea, tablesample  (Stephen Frost <sfrost@snowman.net>)
Re: Gsoc2012 idea, tablesample  (Qi Huang <huangqiyx@hotmail.com>)
List pgsql-hackers
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
enoughthat 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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