On May 24, 2007, at 8:26 PM, Tom Lane wrote:
"Joshua D. Drake" <[EMAIL PROTECTED]> writes:
Tom Lane wrote:
I'm not sure I want to vote for another 10x increase by
default, though.
Outside of longer analyze times, and slightly more space taken up
by the
statistics, what is the downside?
Longer plan times --- several of the selfuncs.c routines grovel
over all
the entries in the pg_statistic row. AFAIK no one's measured the real
impact of that, but it could easily be counterproductive for simple
queries.
The lateness of the hour is suppressing my supposed statistics savvy,
so this may not make sense, but...
Would it be possible to look at a much larger number of samples
during analyze,
then look at the variation in those to generate a reasonable number of
pg_statistic "samples" to represent our estimate of the actual
distribution?
More datapoints for tables where the planner might benefit from it,
fewer
where it wouldn't.
Cheers,
Steve
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