Re: understanding handler::read_time and handler::scan_time

[Sergei Golubchik]

Hi, Zardosht!

On Oct 07, Zardosht Kasheff wrote:
> I realize this may be difficult to answer, but any examples on when
> absolute values matter?

You mean queries ?
I actually only looked at the code, there are places like

      tmp= s->table->file->scan_time();
      tmp= record_count *
         (tmp +
          (s->records - rnd_records)/(double) TIME_FOR_COMPARE);

here a normalized number of records is added to scan_time(),

      index_scan_time= select_limit/rec_per_key *
                       min(rec_per_key, table->file->scan_time());

here scan_time() is compared with rec_per_key,

    scan_time= (double) records / TIME_FOR_COMPARE + 1;
    read_time= (double) head->file->scan_time() + scan_time + 1.1;

here, again, it's added to the normalized number of records.

Regards / Mit vielen Grüßen,
Sergei

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