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 <[email protected]>: > 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
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