06-12-2012
Matching 10 Million file records with 10 Million in other file
Dear All,
I have two files both containing 10 Million records each separated by comma(csv fmt).
One file is input.txt other is status.txt.
Input.txt-> contains fields with one unique id field (primary key we can say)
Status.txt -> contains two fields only:1. unique id and 2. status
problem: match id from input.txt to id from status.txt and update/log the status accordingly in output file.
requirement: need efficient algo for getting the solution in minimal time. tried perl, but system hangs during processing. Pls suggest if there's a workable way to do the same. Is it doable in perl or c/c++/java ?
Thanks.
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LEARN ABOUT DEBIAN
perl::critic::policy::inputoutput::prohibittwoargopen
Perl::Critic::Policy::InputOutput::ProhibitTwoArgOpen(3pUser Contributed Perl DocumentatPerl::Critic::Policy::InputOutput::ProhibitTwoArgOpen(3pm)
NAME
Perl::Critic::Policy::InputOutput::ProhibitTwoArgOpen - Write "open $fh, q{<}, $filename;" instead of "open $fh, "<$filename";".
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
The three-argument form of "open" (introduced in Perl 5.6) prevents subtle bugs that occur when the filename starts with funny characters
like '>' or '<'. The IO::File module provides a nice object-oriented interface to filehandles, which I think is more elegant anyway.
open( $fh, '>output.txt' ); # not ok
open( $fh, q{>}, 'output.txt' ); # ok
use IO::File;
my $fh = IO::File->new( 'output.txt', q{>} ); # even better!
It's also more explicitly clear to define the input mode of the file, as in the difference between these two:
open( $fh, 'foo.txt' ); # BAD: Reader must think what default mode is
open( $fh, '<', 'foo.txt' ); # GOOD: Reader can see open mode
This policy will not complain if the file explicitly states that it is compatible with a version of perl prior to 5.6 via an include
statement, e.g. by having "require 5.005" in it.
CONFIGURATION
This Policy is not configurable except for the standard options.
NOTES
There are two cases in which you are forced to use the two-argument form of open. When re-opening STDIN, STDOUT, or STDERR, and when doing
a safe pipe open, as described in perlipc.
SEE ALSO
IO::Handle
IO::File
AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>
COPYRIGHT
Copyright (c) 2005-2011 Imaginative Software Systems. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
perl v5.14.2 2012-06-07 Perl::Critic::Policy::InputOutput::ProhibitTwoArgOpen(3pm)