Re: Measuring relation free space

On 11/28/2011 05:40 AM, Greg Smith wrote:
> Ignoring fillfactor seems to have even more downsides as I see it.
> Certainly deserves a doc improvement, as well as fixing the
> description of the value so it's clearly a ratio rather than a true
> percentage.

So: I'm very clear on what to do here now:

-Make the computation be in units that match it documetnation
-Take a look at other index types, as well as TOAST, at least to get the
easy ones right.
-Fully confirm the extension upgrade logic works as hoped

That's the must do stuff. Then there's two more features to consider
and do something with if sensible:

-Double check whether there is really a useful role in using
pg_freespace here. I don't think the numbers will be as good, but maybe
we don't care.
-Once the above is all sorted, add a second UI that samples some pages
and extrapolates, ANALYZE-style, rather than hitting everything.

This ones leaves as returned with feedback, feeling pretty good it will
be whipped into good shape for the last 9.2 CommitFest.

--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
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