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Re: A (memory) poor man's <strike>hash</strike> lookup table.

by TimToady (Parson)
on Nov 22, 2003 at 00:07 UTC ( #309076=note: print w/ replies, xml ) Need Help??


in reply to A (memory) poor man's <strike>hash</strike> lookup table.

For another approach, look at Tie::SubstrHash. You'd have to recast your problem as keys of constant length though. Still, it'd be interesting to see a timing comparison.


Comment on Re: A (memory) poor man's <strike>hash</strike> lookup table.
Re: Re: A (memory) poor man's <strike>hash</strike> lookup table.
by BrowserUk (Pope) on Nov 22, 2003 at 09:43 UTC

    The timing comes out to 10 minutes for the insertion and 9.6 minutes for iteration of the million keys.

    use Tie::SubstrHash; tie %hash, 'Tie::SubstrHash', 7, 1, 1_000_000; print time; $hash{ pack 'A7', $_ } = ' ' for 1 .. 1_000_000; print time; 1069489311 1069489911 $n = 0; print time; $n += defined $hash{ pack 'A7', $_ } for 1 .. 1_000_000; print time, $ +/, $n; 1069490448 1069491023 1000000

    I think that it may be possible to improve this a little by updating the module. It uses local several places where my would probably be quicker. Though, I suspect that the main performance hit is the cost of tie rather than the implementation. Part of my reasoning for liking the mechanism I described was that it was simple enough in it's implementation that it could be coded directly avoiding the need for tie.

    I also think that it would be possible to improve the user interface by having the module perform any padding required rather than the caller,


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