Hi, Igor! On Apr 24, Igor Babaev wrote:
On 04/24/2011 01:51 AM, Sergei Golubchik wrote:
In 5.3, record_count* is moved to a separate line, so it should just be
tmp= min(tmp,s->worst_seeks);
But it uses table->file->read_time(). Which is defined as
virtual double read_time(uint index, uint ranges, ha_rows rows) { return rows2double(ranges+rows); }
In the implementation of innodb/xtradb (ha_innobase::read_time) if the parameter rows = 0 , the function returns 0 :(
if (rows <= 2) {
return((double) rows); }
so, when ranges=1 and we pass rows=min(tmp,s->worst_seeks)-1, we get the same value of min(tmp,s->worst_seeks) as the result.
I agree that this -1 is a hack and that logically it should be removed. But it may affect plans and fail quite a few test cases. If it is ok - feel free to fix it and remove -1. Regards, Sergei