in reply to Re^4: Nested greps w/ Perl
in thread Nested greps w/ Perl

And doing that for 8 million people.

Is that 8 million records in the file? Or 8 million people with each having multiple records in the file?

If the former, (roughly) how many records per person? If the latter, what is the total number of records in the file?

Update: Given your test file format with 8 million lines, this one liner does the job in around 35 seconds:

[19:07:51.13] C:\test>wc -l 1178116.dat
8000000 1178116.dat

[19:07:54.92] C:\test>head 1178116.dat
ihpfgx  Z
fxbkfh  Z
kqektt  B
zxburh  Z
zpzafy  Z
nvamqp  Z
umpeky  Z
hyfldc  B
qdapmk  Z
ynlfhg  Z

[19:08:07.28] C:\test>perl -anle"$F[1] eq 'Z' and ++$h{$F[0]} }{ print
+ join ' ', $_, $h{ $_ } for keys %h" 1178116.dat >null
[19:08:42.87] C:\test>

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