Hi Greg,
So I had a thought about how to soften the controversial hard cutoff of 100
for the use of the histogram selectivity. Instead of switching 100% one way or
the other between the two heuristics why not calculate both and combine them.
The larger the sample size from the histogram the more we can weight the
histogram calculation. The smaller the histogram size the more we weight the
heuristic.
My first thought was to scale it linearly so we use 10% of the histogram
sample + 90% of the heuristic for default statistic sizes of 10 samples. That
degenerates to the status quo for 100 samples and up.
Incidentally I hacked up a patch to do this:
Sounds sensible to me, at least much more than a hardcoded magic number
a few people know about...
Cheers
--
Matteo Beccati
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