[Chicago-talk] Performance issue
Warren Lindsey
warren.lindsey at gmail.com
Wed Apr 20 10:03:53 PDT 2011
I assume by your use of <> and print without a filehandle that you are going through pipes and reading from STDIN and writing to STDOUT. I suspect opening input and output file handles will be more efficient. Less data movement between buffers.
Cheers,
Warren
On Apr 20, 2011, at 11:37 AM, Jay Strauss <me at heyjay.com> wrote:
> Hi all,
>
> I have a csv file, with quoted strings (i.e. "field1","field2",...). The file is 3.5M records. I'm running strawberry perl on win7 (not that I think that's the issue). What I need to do is convert any embedded "|" to "-", convert the field delimiter ' "," ' to "|". I know there are cpan mods for parsing csv but my situation is pretty straight forward. I'm doing:
>
> use strict;
>
> while(<>) {
>
> $_ = substr $_, 1, -2; # Remove first and last ", and remove
> # the \n at the same time
> #
>
> s/\|/-/g; # Change embedded "|" into "-"
>
> my @words = split(/\",\"/,$_,-1); # split on the remaining ","
>
> print join("|", @words),"\n";
> }
>
> But it's take what seems like a long time to run (like 15 mins). I'd think this would be an ideal use for Perl, and could rip through the file lickedy split.
>
> I'm I doing something costly in the script above that is making it run so slow?
>
> Thanks
> Jay
>
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