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[Roberto Spadim <roberto@xxxxxxxxxxxxx>]

nice :) maybe part of msql? :) very old times

nice, i will stay updated with this gson project, very interesting and a
very good work :)


2014-05-27 15:35 GMT-03:00 Sergei Golubchik <serg@xxxxxxxxxxx>:

> Hi, Roberto!
>
> On May 27, Roberto Spadim wrote:
> > Hi Sergei!
> > nice :) i'm reading about it
> > just one doubt i didn't understand everything yet
> > there's a read time and a scan time, what the difference? read =
> sequencial
> > read and scan = non sequencial read? or something like table read cost,
> > index read cost?
>
> Yes, the handler methods are:
>
>   virtual double handler::scan_time()
>   { return stats.data_file_length / IO_SIZE + 2; }
>   virtual double handler::read_time(uint index, uint ranges, ha_rows rows)
>   { return ranges+rows; }
>
> these are the default implementations, in the base handler class. Method
> names are historical and *very* old.
>
> The return values are kind of "number of disk seeks". You can see that
> scan_time() assumes a sequential disk read of blocks of IO_SIZE bytes.
>
> While read_time() assumes random reads of 'rows' rows from the data
> file and 'ranges' ranges from the index.
>
> These default implementations, I suspect, predate even MyISAM.
>
> Regards,
> Sergei
>
>


-- 
Roberto Spadim
SPAEmpresarial
Eng. Automação e Controle