jug, no one speaks for 'the group', though some do like to speak louder.
datatype is not an issue in the strictest sense
using updatable values in primary keys, or values that have a meaning beyond
identification, are issues
creating an index on a DNAME column in a departments table (a real table,
not Scott's 4-row table) is not an issue if the index is being created to
support searches on DNAME or to support uniqueness
however, if i use DNAME as a PK (since my analysis tells me it has to be
unique) instead of a system-assigned, or even a user-assigned number i will
have the following issues:
[_] larger values in the index
[_] potential updates as department names change
[_] cascading updates to other tables with FK's referencing the updated PK
[_] potential table structure revisions as business rules change (if
department names are no longer unique, it's a lot easier to drop a unique
constraint than to restructure the table with a new PK -- and new FK's)
[_] etc., etc.
and even if i use a short user-assigned mnemonic (which i sometimes will
do), we run the risk of PK updates (to be religiously avoided) or of
imbedding intelligence in the PK. for example, why is one department called
S023 and another called M023? did we miss an attribute that should group the
departments by business unit or such, i.e., SALES and MANUFACTURING (or is
that M for MARKETING?)
some of these issues are important data modeling issues, others are
implementation and tuning issues
where to look in the manuals? read up in the Concepts, DBA, and Tuning
manuals. chapter and verse? interesting analogy. sometimes issues have to be
dealt with based on breadth and depth of experience and familiarity with a
number of concepts, principals, and scenarios -- when you've got serious
concerns you need to research relevant topics (in this case indexes,
datatypes, optimizer, constraints) and do some of your own testing (see
Jonathan Lewis' website
www.jcomp.demon.co.uk for some excellent info on
research, testing, and logical analysis of Oracle issues). then you'll also
be able to benefit more from other people's observations, and filter our
what is relevant and what is not.
-- mcs
"Jug Ray" <jr*****@yahoo.com> wrote in message
news:fd**************************@posting.google.c om...
Frank <fv********@netscape.net> wrote in message
news:<bn**********@news1.tilbu1.nb.home.nl>...
Because it's a non-issue. All the answers are there (OK, OK - some
coding was actually left to the OP).
Give a man something to eat, and he will be hungry tomorrow,
teach him how to fidh, and he'll never be hungry again.
Or words the like.
Generally, we're not here to hold hands...
is the datatype an issue in indexes or not
i am looking also for an answer to that one
for a long time, tell me where it is in the manual
chapter, verses, book of ... as you seem to speak
for the group at large
what are you trying to say in "Give a man..."
I know its all there but can make sense of what you say
Jug