Random thoughts from Random_Walk

Do you have to 

File1 --> Randomise --> File1'
File2 --> Randomise --> File2'
.
.
Filen --> Randomise --> Filen'

[download]
or more a case of 
File1 --+              + Filea
File2 --+-> Randomise -+ Fileb
....    |              | ....
Filen --+              + Filez

[download]
How fast is the script that uses the randomised data capable of using it ? Do you really have to rewrite the entire files ? perhaps you can provide a script that returns random lines from them to STDOUT (and keeps a record so it does not give the same twice).

I guess your increasing mem usage comes from the record of which lines you already output. You could return some lines (perhaps 10%), then re-write the source files without the used up lines, rinse repeat...

You could clobber the start of the lines you have used with some unique token XXX-Clobbered-XXX then you do not need to store the used lines record in RAM, of course as you get past 50% your random line will hit a clobbered one more often than not so a re-write of the source data purging the used lines would still be required at some point.

You could put in more RAM or faster disk :)

Cheers,
R.

In reply to Re: Strategy for randomizing large files via sysseek by Random_Walk
in thread Strategy for randomizing large files via sysseek by Anonymous Monk

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