Re: sorter script [was: Frustrated newbie question]

From: Drieux (drieux_at_wetware.com)
Date: 12/11/03 

Date: Wed, 10 Dec 2003 16:52:51 -0800
To: Perl Perl <beginners@perl.org>

On Dec 9, 2003, at 4:20 PM, R. Joseph Newton wrote:
[..]
> To me hashes are like sausage to a carnivore--I love the end product,
> but
> have no desire to look too closely at the process.
[..]

first the last,
the schwartzian transformation I included
was from the "perldoc -q sort" as a way of
noting that there are some interesting things
that can be done, if done well, in memory.

So on top of the usual 'portability' sets
of issues there is also the problem that
some 'sort' utilities will 'fault' to an
I/O event to write out intermediary stage
results, so as to save on memory usage.

The PPT version of sort does not take a
-T <dir> option to allow one to fan out
the intermediary stages, nor does it offer
a -ykmem option... caveat emptor.

Warning: Serious GEEKING...

I like your idea of 'shape()' - in the abstract -
as a way of 'visualizing' the problem. Since that
does point back to the 'design elements' of a
well done 'database solution'. { for me, many
of the 'implementation details' of DataBaseFoo,
should be handled, like hashes, as things we do,
but prefer not to talk about in polite society. }

The problem with 'aesthetics' - my 'ugly sort'
kvetch, is that at times a bit of brute force
is 'good enough' - and can be better than the
most 'elegant' of looking algorithms.

One case in particular that left scars was what
technically was an 'elegant' SQL query a co-worker
had constructed. Since it seemed to be simpler. The problem was
that it meant a series of "interesting" join statements
that bogged the database engine down. { some of that
was due to bad implementation on the db engine. }
Rather than taking the 'less elegant' "bute force"
approach of two 'get foo' things that would dump
more bits on the wire, but less weight on the db engine,
and the post processing was done on 'cheaper'
support servers.

So while a given algorithm may map out as
O(<foo_val>) in the logical analysis, depending
upon what else is in play, it may have an impact
that is disproportionate.

ciao
drieux 

---

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