in reply to Memory Optimization

For a complex hash you'll probably want to use Storable qw(nstore);. nstore is more portable than store and you can still use the same retrieve function. You might need to experiment but below are snippets from code that I currently use. The resulting file is roughly 2.2 times larger than a fixed length text file of the same data. Excerpts from The Perl Cookbook gives some explanation. To save the hash structure to disk: 
use strict;
use Storable qw(nstore);

my %hash = my_build_hash_sub();
nstore (\%hash, "hash.nstore.dat");

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To reload hash from disk: 
use strict;
use Storable;

my %hash = %{ retrieve("hash.nstore.dat") };

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--Jim

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Re: Re: Memory Optimization
by Juerd (Abbot) on Dec 30, 2001 at 06:02 UTC
    Speaking of memory optimizations, my %hash = my_build_hash_sub(); will toss around a list and eat memory for that. Returning a reference to a hash would in many cases be more efficient than returning a list of keys/values. 

    2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$

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[d/l]
      You're absolutely right. My concern when these snippets were written was not memory optimization so much as decreasing IO read/writes times.

      Thanks for the clarification. I'll look into rewriting the hash generation subs to use references.

      --Jim

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