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Fixed bug mdev-4350.

Browse Source 
Wrong formulas used by the function Histogram::point_selectivity()
could result in a negative value of selectivity returned by the
function.
This commit is contained in:
Igor Babaev
2013-04-03 20:00:10 -07:00
parent 911749ad6f
commit d62ee4e970
4 changed files with 123 additions and 18 deletions
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14
sql/sql_statistics.h
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@ -152,10 +152,10 @@ private:
uint val= (uint) (pos * prec_factor());
int lp= 0;
int rp= get_width() - 1;
uint i= 0;
for (int d= get_width() / 2 ; d; d= (rp - lp) / 2)
int d= get_width() / 2;
uint i= lp + d;
for ( ; d; d= (rp - lp) / 2, i= lp + d)
{
i= lp + d;
if (val == get_value(i))
break;
if (val < get_value(i))
@ -237,9 +237,11 @@ public:
uint max= min;
while (max + 1 < get_width() && get_value(max + 1) == get_value(max))
max++;
double width= ((max + 1 == get_width() ? 1.0 : get_value(max)) -
(min == 0 ? 0.0 : get_value(min-1))) *
((double) 1.0 / prec_factor());
double inv_prec_factor= (double) 1.0 / prec_factor();
double width= (max + 1 == get_width() ?
1.0 : get_value(max) * inv_prec_factor) -
(min == 0 ?
0.0 : get_value(min-1) * inv_prec_factor);
sel= avg_sel * (bucket_sel * (max + 1 - min)) / width;
return sel;
}