Depends upon your filing system, but 2 x 2-digits means a max of 100 in the lower levels and 10,000 in the top. 2 x 3-digit, gives 1000 in teh lower levels and 100 in the top. Every filesystem I am aware of will handle those numbers with ease.
The latter probably works better for performance, but you'd have to do a few tests to be sure.
On my system it is much of a muchness at around 3 milliseconds per lookup/increment either way:
#! perl -slw
use strict;
use Time::HiRes qw[ time ];
mkdir 'myroot';
for my $l1 ( '00' .. '09' ) {
mkdir "myroot/$l1";
for my $l2 ( '00' .. '09' ) {
mkdir "myroot/$l1/$l2";
mkdir "myroot/$l1/$l2/$l1$l2$_" for '000' .. '999';
mkdir "myroot/$l1/$l2/$l1$l2$_/1" for '000' .. '999';
}
}
my $start = time;
for( 1 .. 1000 ) {
my $id = sprintf "%02u%02u%03u", int( rand 10 ), int( rand 10 ), in
+t( rand 1000 );
my( $l1, $l2 ) = unpack 'a2a2', $id;
opendir D, "myroot/$l1/$l2/$id/";
readdir D; readdir D; ## get rid of '.' & '..'
my $count = readdir D;
rename "myroot/$l1/$l2/$id/" . $count, "myroot/$l1/$l2/$id/" . ++$c
+ount
or warn "$! : $id : $count";
closedir D;
}
printf "2x2x7 took %f secs/lookup&increment\n", ( time() - $start ) /
+1000;
system "rd /q /s myroot";
mkdir 'myroot';
for my $l1 ( '000' .. '009' ) {
mkdir "myroot/$l1";
for my $l2 ( '000' .. '009' ) {
mkdir "myroot/$l1/$l2";
mkdir "myroot/$l1/$l2/$l1$l2$_" for '0' .. '9';
mkdir "myroot/$l1/$l2/$l1$l2$_/1" for '0' .. '9';
}
}
$start = time;
for( 1 .. 1000 ) {
my $id = sprintf "%03u%03u%01u", int( rand 10 ), int( rand 10 ), in
+t( rand 10 );
my( $l1, $l2 ) = unpack 'a3a3', $id;
opendir D, "myroot/$l1/$l2/$id/" or warn "$! : myroot/$l1/$l2/$id/"
+;
readdir D; readdir D; ## get rid of '.' & '..'
my $count = readdir D;
rename "myroot/$l1/$l2/$id/" . $count, "myroot/$l1/$l2/$id/" . ++$c
+ount
or warn "$! : $id : $count";
closedir D;
}
printf "3x3x7 took %f secs/lookup&increment\n", ( time() - $start ) /
+1000;
system "rd /q /s myroot";
__END__
C:\test>1032393
2x2x7 took 0.002671 secs/lookup&increment
3x3x7 took 0.002761 secs/lookup&increment
C:\test>1032393
2x2x7 took 0.002628 secs/lookup&increment
3x3x7 took 0.003111 secs/lookup&increment
BTW: Please note the additional readdir D; readdir D; ## get rid of '.' & '..' which I forgot above.
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