> Okay, although given the track record of page-based sampling for
> n-distinct, it's a bit like looking for your keys under the streetlight,
> rather than in the alley where you dropped them :-)

Bad analogy, but funny.

The issue with page-based vs. pure random sampling is that to do, for example, 
10% of rows purely randomly would actually mean loading 50% of pages.  With 
20% of rows, you might as well scan the whole table.

Unless, of course, we use indexes for sampling, which seems like a *really 
good* idea to me ....


Josh Berkus
Aglio Database Solutions
San Francisco

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