Re: DirectoryString versus IA5 String

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

At 08:08 AM 7/5/2004, Rich Graves wrote:
>(I'm using openldap 2.2.14)
>
>What should I consider when deciding whether to define local attributes as
>
>SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 Directory String (UTF-8)
>SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 IA5 String
>SYNTAX 1.3.6.1.4.1.1466.115.121.1.36 Numeric String
>SYNTAX 1.3.6.1.4.1.1466.115.121.1.40 Octet String
>SYNTAX 1.3.6.1.4.1.1466.115.121.1.44 Printable String
>
>Is it correct to think that if I "know" the data is restricted to ASCII, 
>then the IA5 string version will perform a little better?

In slapd(8) of today, the amount of work to validate, normalize,
match, or otherwise process IA5 Strings is basically on par
with the amount of work to process UTF-8 Directory Strings
which have been restricted to ASCII characters.  In slapd(8)
of the future (e.g, post implementation of LDAPprep
<draft-ietf-ldapbis-strprep>), this should hold true as well.

Even if there were a difference, I would generally advise against
using a syntax other than Directory String to represent character
data in the directory.  However, as reasons for this are not
specific to OpenLDAP Software, so I won't elaborate more on this
here.

Kurt