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How to make awk command faster?

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Top Forums Shell Programming and Scripting How to make awk command faster?
# 1  
Old 09-05-2017
How to make awk command faster?
I have the below command which is referring a large file and it is taking 3 hours to run. Can something be done to make this command faster.
Code:
 awk -F ',' '{OFS=","}{ if ($13 == "9999") print $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12 }' ${NLAP_TEMP}/hist1.out|sort -T ${NLAP_TEMP} |uniq> ${NLAP_TEMP}/hist2.final

The hist1.out file looks as below
Code:
 rp01_2017,1002302_43,1,103,0074,0,0,0,0,0,0,18,9994
rp01_2017,1002302_43,1,103,0077,0,0,0,0,0,0,18,9999
rp01_2018,1002302_43,1,103,0074,0,0,0,0,0,0,9,9994
rp01_2018,1002302_43,1,103,0077,0,0,0,0,0,0,9,9999
rp10_2017,1002302_43,1,103,0074,0,0,0,0,0,0,16,9994
rp10_2017,1002302_43,1,103,0077,0,0,0,0,0,0,16,9999
rp10_2018,1002302_43,1,103,0074,0,0,0,0,0,0,4,9994
rp10_2018,1002302_43,1,103,0077,0,0,0,0,0,0,4,9999
rp18_2017,1002302_43,1,103,0074,0,0,0,0,0,0,14,9994
rp18_2017,1002302_43,1,103,0077,0,0,0,0,0,0,14,9999


Moderator's Comments:
Mod Comment Welcome! Please use code tags for your code and data, thanks


---------- Post updated at 03:52 AM ---------- Previous update was at 03:16 AM ----------

Code:
 awk -F ',' '{OFS=","}{ if ($13 == "9999") print $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12 }' ${NLAP_TEMP}/hist1.out|sort -T ${NLAP_TEMP} |uniq> ${NLAP_TEMP}/hist2.final

Last edited by vbe; 09-05-2017 at 05:40 AM.. Reason: code tags
# 2  
Old 09-05-2017
Would using sed be any quicker?
Code:
sed -n '/,9999$/ s///p' ${NLAP_TEMP}/hist1.out|sort -u -T ${NLAP_TEMP}> ${NLAP_TEMP}/hist2.final

Basically if it matches the last field it deletes that field and then prints the modified line. Also by using sort -u rather than sort | uniq you reduce the number of processes in the pipeline by one.

Andrew
# 3  
Old 09-05-2017
A BEGIN section is only executed once (at the beginning).
And maybe sort can be skipped by just eliminating duplicates?
Code:
awk 'BEGIN { FS=OFS="," } ($13 == "9999" && !($0 in s)) { s[$0]; print $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12 }' ${NLAP_TEMP}/hist1.out > ${NLAP_TEMP}/hist2.final

The following variant works like the previous sed solution
Code:
awk '(sub(/,9999$/,"") && !($0 in s)) { s[$0]; print }' ${NLAP_TEMP}/hist1.out > ${NLAP_TEMP}/hist2.final

# 4  
Old 09-06-2017
Hoping that sort has advanced algorithms:
Code:
sort -t, -k13r file | awk -F, 'sub (/,9999$/, _) {print; next} {exit}'
rp01_2017,1002302_43,1,103,0077,0,0,0,0,0,0,18
rp01_2018,1002302_43,1,103,0077,0,0,0,0,0,0,9
rp10_2017,1002302_43,1,103,0077,0,0,0,0,0,0,16
rp10_2018,1002302_43,1,103,0077,0,0,0,0,0,0,4
rp18_2017,1002302_43,1,103,0077,0,0,0,0,0,0,14

# 5  
Old 09-07-2017
Thank you all for your response


The below command has really helped in reducing the time.Would this also sort the rows or do we need to use sort after this?


Code:
awk 'BEGIN { FS=OFS="," } ($13 == "9999" && !($0 in s)) { s[$0]; print $1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12 }' ${NLAP_TEMP}/hist1.out > ${NLAP_TEMP}/hist2.final


Moderator's Comments:
Mod Comment Please use CODE tags as required by forum rules!
Last edited by RudiC; 09-07-2017 at 11:39 AM.. Reason: Added CODE tags.
# 6  
Old 09-07-2017
That script would not sort the rows as it was not asked to do.

It would be interesting to see a comparison between the different approaches. Could you time each and post the results?
# 7  
Old 09-07-2017
Quote:
Originally Posted by Peu Mukherjee
Thank you all for your response

The below command has really helped in reducing the time. Would this also sort the rows or do we need to use sort after this?
It reduced time by not sorting it. That's liable to be what took the lion's share of the time.

If you need it sorted, and need it sorted faster, point sort to a different disk for temporary space with -T /path/to/folder. Using a different disk for temp space will increase the speed your data can be read.

GNU sort also has a --parallel option, but this is not much help unless you have extraordinarily fast disks.
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