[Xapian-discuss] How many docs to feed to an RSet?
matthew at mysociety.org
Mon Mar 3 18:56:05 GMT 2008
Richard Boulton wrote:
> The best answer is to play around, experiment, and see what seems to
> work for you.
Something that will probably have to wait for some future time then :-)
> Incidentally, if you're just passing 500 to get an accurate result
> count, you might want to try using the "checkatleast" parameter for
> that, instead. eg: get_mset(0,20,500).
Ah, thanks, presumably a hangover from when we were using a much older
version of Xapian. It seems to be behaving oddly, though. With this PHP code
for the values of N 0, 100, 500, and 1000:
$m = $enquire->get_mset(0, 20, N);
print $m->get_matches_estimated(). ' ';
432 453 465 510
when the actual number of results is 463. The wiki says that if the number
of results is less than checkatleast, get_matches_estimated() should return
the exact result. As I increase the first argument to get_mset() it
eventually starts returning the right result.
It's defaulting to collapse on value 3, in case that is doing something; if
I switch that off, everything returns 594, the presumably correct result
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