Re: Gsoc2012 idea, tablesample - Mailing list pgsql-hackers

From Stephen Frost
Subject Re: Gsoc2012 idea, tablesample
Date
Msg-id 20120419124751.GX1267@tamriel.snowman.net
Whole thread Raw
In response to Re: Gsoc2012 idea, tablesample  (Sandro Santilli <strk@keybit.net>)
Responses Re: Gsoc2012 idea, tablesample  (Sandro Santilli <strk@keybit.net>)
List pgsql-hackers
* Sandro Santilli (strk@keybit.net) wrote:
> Actually a random sample would really be representative of the data
> distribution. What the type analyzer gets is a sample and that sample
> is what the estimator looks at to answer the question:

That might work if all you have is point data, but lines, polygons, etc,
you're typically going to want to see, just not at the same resolution..
At least, when you're talking about 'zoom-out' tiles, which is what this
was about up thread.

> I'm looking for a way to fetch random samples these days so I confirm
> the need for a quick way to fetch the same sample that "analyze"
> command fetches but at SQL level.

I'm all for supporting that and implementing this feature, I just don't
think it's going to be all that useful for zoom-out tiles when complex
geometries are involved.
Thanks,
    Stephen

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