сlose all
lnSec = seconds()
use FILEA order NOM
go top
do while !eof()
   skip
enddo
use FILEB order NOM
go top
do while !eof()
   skip
enddo
? 'Идеальное время: ', seconds() - lnSec

сlose data all
lnSec = seconds()
use FILEA order NOM in  0 
use FILEB order NOM in  0 
go top in FILEA
go top in FILEB
do while !eof('FILEA') and !eof('FILEB')
   if !eof('FILEA')
      skip in FILEA
   endif
   if !eof('FILEB')
      skip in FILEB
   endif
enddo
? 'Идеальное время: ', seconds() - lnSec

close data all
use zak &&  1   134   952  записи
* делаем два разных файла
if !file('FILEA.dbf')
	copy to FILEA for recno() %  3  !=  0 
endif
sele  0 
use FILEA excl &&  756   117  записей
if tagcount() =  0 
	index on nSum tag nSum
else
	set order to nSum
endif
sele zak
if !file('FILEB.dbf')
	copy to FILEB for recno() %  5  !=  0 
endif
sele  0 
use FILEB excl &&  902   496  записей
if tagcount() =  0 
	index on nSum tag nSum
else
	set order to nSum
endif
****************************************************
? 'Тест 1'
lnSec = seconds()
SELECT aa.nSum FROM ( ;
	SELECT distinct nSum FROM fileA) aa ;
		inner join ;
	(SELECT nSum FROM fileB GROUP BY nSum HAVING COUNT(nSum) >  1 ) bb ;
		on aa.nSum = bb.nSum;
	into cursor res1
? 'Время1: ', seconds() - lnSec &&  6 . 71  сек
****************************************************
? 'Тест 2'
lnSec = seconds()
create cursor res2 (nSum n( 10 , 2 ))
sele FILEA
go top
sele FILEB
go top
lnPrevSumB =  9999999999 
do while .t.
	if FILEA.nSum < FILEB.nSum
		skip in FILEA
		if eof('FILEA')
			exit
		endif
	else
		if FILEB.nSum = lnPrevSumB and FILEA.nSum = FILEB.nSum and res2.nSum != lnPrevSumB
			append Blank in res2
			repl in res2 nSum with lnPrevSumB
		else
			lnPrevSumB = FILEB.nSum
		endif
		skip in FILEB
		if eof('FILEB')
			exit
		endif
	endif
enddo
? 'Время2: ', seconds() - lnSec &&  5 . 90  сек