Re: Reducing the overhead of NUMERIC data

On Thu, Nov 03, 2005 at 09:17:43PM -0500, Tom Lane wrote:
> Gregory Maxwell <gmaxwell(at)gmail(dot)com> writes:
> > Another way to look at this is in the context of compression: With
> > unicode, characters are really 32bit values... But only a small range
> > of these values is common. So we store and work with them in a
> > compressed format, UTF-8.
> > As such it might be more interesting to ask some other questions like:
> > are we using the best compression algorithm for the application, and,
> > why do we sometimes stack two compression algorithms?
> Actually, the real reason we use UTF-8 and not any of the
> sorta-fixed-size representations of Unicode is that the backend is by
> and large an ASCII, null-terminated-string engine. *All* of the
> supported backend encodings are ASCII-superset codes. Making
> everything null-safe in order to allow use of UCS2 or UCS4 would be
> a huge amount of work, and the benefit is at best questionable.

Perhaps on a side note - my intuition (which sometimes lies) would tell
me that, if the above is true, the backend is doing unnecessary copies
of read-only data, if only, to insert a '\0' at the end of the strings.
Is this true?

I'm thinking along the lines of the other threads that speak of PostgreSQL
being CPU or I/O bound, not disk bound, for many sorts of operations. Is
PostgreSQL unnecessary copying string data around (and other data, I would
assume).

Cheers,
mark

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