Re: [MacPerl] deleting a line again

[A K Suska <aksuska@insideflyer.com>]

> Files are not monolithic lines of bits on a platter, they are
> distributed among sectors.  It seems to me that with the right
> filesystem, you ought to be able to modify but one sector.

Well, you actually can with extremely low level calls, but you still have
the problem where a "line" crosses multiple sectors. The resulting code
would probably be so inefficient it would be better to rewrite the whole
file (unless it is rather large)

> Yeah, yeah, that would leave an un-full sector which classically can only be
> the last one, but: a) is that true in all modern filesystems (hfs+ for
> example)? b) need that always be true?

Well, it doesn't always work that way, but if you have heard of a "bad"
thing called "fragmentation", you are talking about a file system that
fragments on a dime, and is therefore very inefficient.

There are very efficient and fast techniques for expanding/collapsing data
files that are used in the better database systems, so you are better off
looking at those rather than wishing for a lousy file system that would run
much slower.

-K


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