Re: dbms_HASH...or something like it?...comparing data...

  • From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Sat, 22 Jan 2005 23:13:11 -0000

You could have a look at procedure
    dbms_utility.get_hash_value()
described in dbmsutil.sql

This turns an input string into a number.

Make sure your developer is aware that
two items that hash to the same value do
not necessarily hold the same original value.


Regards

Jonathan Lewis

http://www.jlcomp.demon.co.uk/faq/ind_faq.html
The Co-operative Oracle Users' FAQ

http://www.jlcomp.demon.co.uk/seminar.html
Public Appearances - schedule updated Dec 23rd 2004






----- Original Message ----- 
From: "Marquez, Chris" <CMarquez@xxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Saturday, January 22, 2005 11:03 PM
Subject: dbms_HASH...or something like it?...comparing data...



Need some help.

Developer has a wide table...20 columns.
He would like to add a 21st column to the table.
Then he would like to (be able to) store the first=20
20 columns data in concatenated form in the 21st column.
For example;
col1, col2, col3
Joe,Smith,JoeSmith

No problem PL/SQL program can handle this, BUT
he would rather store the 20 concatenated columns in=20
a simpler, tighter form. He suggested "hashing" the=20
20 concatenated columns to (I guess) an Alphanumeric string?

And given that this is possible, what would be the=20
best/required data type for the hashed data?

Why you ask?
Because he want to be able to compare rows=20
(against new data) simply and quickly without selecting and=20
concatenating all 20 originally columns.

So he would store the hashed version of a row (data) on Insert.
Then on Update using a function hash the update data  and compare
it to the  already hashed value in the row.
=20
Any help is appreciated?
Any other solution is appreciated, BUT his program is limited and=20
can only S,I,U,D and call PROCEDURES or FUNCTIONS.

Please reply directly to me as well as to the list.

Thanks in advance,

Chris Marquez
Oracle DBA
HEYMONitor(tm) - heymonitor.com
"Oracle Monitoring & Alerting Solution"

--
//www.freelists.org/webpage/oracle-l

--
//www.freelists.org/webpage/oracle-l

Other related posts: