From: | Marc Herbert <Marc(dot)Herbert(at)continuent(dot)com> |
---|---|
To: | pgsql-jdbc(at)postgresql(dot)org |
Subject: | Re: binary protocol was Performance problem with timestamps in result sets |
Date: | 2006-03-10 15:42:49 |
Message-ID: | khjirqm5mrq.fsf@meije.emic.fr |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-jdbc |
"Thomas Dudziak" <tomdzk(at)gmail(dot)com> writes:
> On 3/9/06, mikael-aronsson <mikael-aronsson(at)telia(dot)com> wrote:
>> How about the actual transport cost difference between text and binary
>> protocols ? it may not be any big difference though, and many times text
>> representation can be smaller then a binary protocol.
>
> Really ? I would have thought its vice versa. E.g. a float is usualy 4
> (or 8) bytes in binary, but can be a lot longer in text depending on
> the format.
To represent binary IEEE754's floats (4 bytes) without loss the
maximum required number of base10 digits is 9. For IEEE754's doubles
(8 bytes) it's 17. I don't know what is the "average" required number
of digits.
Of course using one byte-character per base10 digit is a waste of
space... you could gzip or BCD-encode the string :-)
References:
- "What Every Computer Scientist Should Know About Floating Point
Arithmetic" 1991 - David Goldberg
- paragraph "Conversions" at:
<http://www2.hursley.ibm.com/decimal/>
From | Date | Subject | |
---|---|---|---|
Next Message | Marc Herbert | 2006-03-10 15:49:44 | Re: binary protocol was Performance problem with timestamps in result sets |
Previous Message | Markus Schaber | 2006-03-10 09:58:06 | Re: binary protocol was Performance problem with timestamps |