I just faced the same problem. With a few lines, I moved my ~4GB hash from RAM to disc: 

use DB_File;
my $db     = '/path/to/hash.db';
my %hash;
tie (%hash, "DB_File", $db, $DB_BTREE) or die("Unable to tie $db: $!")
+;
# do things with hash
untie %hash;

[download]

Note that $DB_BTREE format is a lot faster than the default, $DB_HASH. (Twice as fast, in my benchmarks.) See also 152966, and the thread leading up to it.

In reply to Re: System out of memory while storing huge amount of data by hbm
in thread System out of memory while storing huge amount of data by kalyanrajsista

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