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Top Forums UNIX for Dummies Questions & Answers Speeding/Optimizing GREP search on CSV files Post 302450972 by matrixmadhan on Sunday 5th of September 2010 05:57:41 AM
Old 09-05-2010
Quote:
Originally Posted by bartus11
You can try all of these, and see which one is the fastest:
Code:
awk -F, '$15$16$17$18~"book34"' /home/data/books/*

Code:
 perl -F, -anle 'print $_ if ($F[14].$F[15].$F[16].$F[17])=~/book34/' /home/data/books/*

Am not really sure, how this would make the search faster than the usual grep? There is no bypass or pruning to make it faster.

I could not think of a better apart approach from pruning the "literal search in the record" once a match is found or not found in the record at the expected field.
For ex:
When searching for 10th field in a record with 20 fields, don't continue searching for the pattern space even after the 10th field just prune the search and continue with the next record.
I agree this is not a great way but it will definitely make the search a bit faster.
 

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ZGREP(1)						      General Commands Manual							  ZGREP(1)

NAME
zgrep - search possibly compressed files for a regular expression SYNOPSIS
zgrep [ grep_options ] [ -e ] pattern filename... DESCRIPTION
Zgrep is used to invoke the grep on compress'ed or gzip'ed files. All options specified are passed directly to grep. If no file is speci- fied, then the standard input is decompressed if necessary and fed to grep. Otherwise the given files are uncompressed if necessary and fed to grep. If zgrep is invoked as zegrep or zfgrep then egrep or fgrep is used instead of grep. If the GREP environment variable is set, zgrep uses it as the grep program to be invoked. For example: for sh: GREP=fgrep zgrep string files for csh: (setenv GREP fgrep; zgrep string files) AUTHOR
Charles Levert (charles@comm.polymtl.ca) SEE ALSO
grep(1), egrep(1), fgrep(1), zdiff(1), zmore(1), znew(1), zforce(1), gzip(1), gzexe(1) ZGREP(1)
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