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Full Discussion: Honey, I broke awk! (duplicate line removal in 30M line 3.7GB csv file)
Top Forums Shell Programming and Scripting Honey, I broke awk! (duplicate line removal in 30M line 3.7GB csv file) Post 302894671 by DGPickett on Wednesday 26th of March 2014 04:07:49 PM
Old 03-26-2014
If I recall correctly, cygwin and win7 not -64 is 32 bit, so 'a' may get too big for the address space of the awk process. Depending on ram size, it might eventually thrash a bit. The awk solution, a hash map, does not support parallism.

The classic, robust solution is 'sort -u <file_set>' but tends to be slower. You can parallelize the sort with a command of the form:
Code:
sort -mu <( sort -u <file_set_1> )  <( sort -u <file_set_2> ) <( sort -u <file_set_3> ) . . . .

where the nicer ksh or bash makes named pipes of the '<(...)' that run concurrently. I like twice the core count <(sort)'s, assuming 50% i/o delay. The final pass of the <(sort)'s feeds the sort -m merge parent.

ETL programs like Ab Initio know how to tell parallel processes to split up big files and process each part separately, even when the files are linefeed delimited (they all agree to search up (or down) for the dividing linefeed closest to N bytes down file). Does anyone know of a utility that can split a file this way (without reading it sequentially)? 'GNU parallel?'
 

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LEARN ABOUT DEBIAN

dpkg-ruby

DPKG-RUBY(1)						      General Commands Manual						      DPKG-RUBY(1)

NAME

       dpkg-ruby - Utility to read a dpkg style db file, dpkg-awk clone

SYNOPSIS

       dpkg-ruby  [(-f|--file) filename] [(-d|--debug) ##] [(-s|--sort) list] [(-n|--numeric) list] [(-rs|--rec_sep) ??] '<fieldname>:<regex>' ...
       -- <out_fieldname> ..

DESCRIPTION

       dpkg-ruby Parses a dpkg status file(or other similarly formated file) and outputs the resulting records.  It can use  regex  on	the  field
       values to limit the returned records, and it can also be told which fields to output.  As another option, it can sort the matched fields.

OPTIONS

       -f filename
       --file filename
	      The file to parse.  The default is /var/lib/dpkg/status.

       -d [#]
       --debug [#]
	      Each time this is specified, it increased the debug level.

       -s field(s)
       --sort field(s)
	      A space or comma separated list of fields to sort on.

       -n field(s)
       --numeric field(s)
	      A space or comma separated list of fields that should be interpreted as numeric in value.

       -rs ??
       --rec_sep ??
	      Output this string at the end of each output paragraph.

       -h
       --help Display some help.

       fieldname
	      The fields from the file, that are matched with the regex given.	The fieldnames are case insensitive.

       out_fieldname
	      The  fields  from the file, that are outputted for each record.  If the first field listed is begins with ^, then the list that fol-
	      lows are fields NOT to be outputted.

BUGS

       Be warned that the author has only a shallow understanding of the dpkg packaging system, so there are probably tons of bugs  in	this  pro-
       gram.

       This  program  comes with no warranties.  If running this program causes fire and brimstone to rain down upon the earth, you will be on our
       own.

       This program accesses the dpkg database directly in places, querying for data that cannot be gotten via dpkg.

AUTHOR

       Fumitoshi UKAI <ukai@debian.or.jp>.  This manual page are based on (or almost copy from :) dpkg-awk(1) manual written by Adam  Heath  <doo-
       gie@debian.org>

DEBIAN
								 Debian Utilities						      DPKG-RUBY(1)
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