use Storable;
store \%table, 'file';
$hashref = retrieve('file');
[download]

Check out DBM::Deep which will allow you to save your hash as a binary file with a very fast lookup.

thanks, all good suggestions.

Allasso

A major defect of this idea is that, all data are virtually loaded in memory all the time. Unless the amount of searchable index is limited, I do not consider this as a workable solution.

Use a DB in this case, and leave the momery management to the DB.

You're looking for a serializer.

See also: How can I visualize my complex data structure?

See also this discussion on stackoverflow.com for a comparison of YAML, JSON, XML, Storable.

Strictly speaking, your inquiry is ambiguous.   The word, “hash,” could mean “a Perl data structure,” or it could mean “(say...) an MD5 or SHA1 digest.”

It's not ambiguous at all - it says "hash or array", the word "array" gives context to the intended meaning of "hash". Perl uses context too, doesn't it ;)

Not to nit-pick here... :-D ... but if someone were determined to misunderstand the OP, it would still be possible to do so.   ;-D

The specific thing that is triggering my uncertainty is the comment, “to use as a search key.”   You probably wouldn’t be expecting to use a JSON-string as a search key; but a SHA1 digest, you might.

It’s kinda like the old saw about a computer program finding five different valid parses to the string, “Time flies like an arrow.”   You could even parse “save hash to a file” in two different ways:   save(hash, to_file) or save(hash(file)).

Aww, heck ... obviously, it is time for more coffee.

TMTOWTCY = There's More Than One Way To Confuse Yourself