$ perl -I ~/perl5/lib/perl5/ llilsql.pl --threads=1 big{1,2,3}.txt | cksum
Tie::Hash::DBD SQLite database - start
fixed string length=12, threads=1, maps=32
get properties   :    41.352 secs
pack properties  :     5.897 secs
sort packed data :     1.164 secs
write stdout     :     3.602 secs
total time       :    52.017 secs
    count lines  : 10545600
    count unique : 10367603
2956888413 93308427

$ perl -I ~/perl5/lib/perl5/ llilsql.pl --threads=8 big{1,2,3}.txt | cksum
Tie::Hash::DBD SQLite database - start
fixed string length=12, threads=8, maps=32
get properties   :     5.572 secs
pack properties  :     0.856 secs
sort packed data :     1.173 secs
write stdout     :     0.719 secs
total time       :     8.323 secs
    count lines  : 10545600
    count unique : 10367603
2956888413 93308427

$ perl -I ~/perl5/lib/perl5/ llilsql.pl --threads=16 --maps=64 big{1,2,3}.txt | cksum
Tie::Hash::DBD SQLite database - start
fixed string length=12, threads=16, maps=64
get properties   :     3.140 secs
pack properties  :     0.533 secs
sort packed data :     1.175 secs
write stdout     :     0.395 secs
total time       :     5.247 secs
    count lines  : 10545600
    count unique : 10367603
2956888413 93308427