RE: Design Issue - Quick response appreciated

From: Greg Solomon <greg.solomon_at_betfair.com>
Date: Mon, 24 Sep 2001 07:38:15 -0700
Message-ID: <F001.00396282.20010924071025@fatcity.com>

Probably stating the obvious here, but if the account can change several times, it may make sense to put the first prior id into all the records. Suppose that when you create a new account, you populate prior id with the value from the id field. Then your query gets nice and simple: select * from transaction where prior_id = XXX;

If you're going to do this, then prior id becomes a slightly confusing name for the field; something like group id may be clearer.

HTH GS

-----Original Message-----

Sent: Saturday, 22 September 2001 06:05
To: Multiple recipients of list ORACLE-L

Rao,

Since the primary key value(s) can change then it cannot be the primary key. You have to use a surrogate key. That solves that design rule.
When the user changes HP to IBM, why are you inserting a new record? Why cant you just update HP to IBM? If, for some reason, you have to insert a record, say the other values in the record change, then I would create a "PRIOR_ID" field, like someone else suggested, which would point to the "HP" record's ID. This field sould also be foreign keyed to the ID column.

Chris
"May Oracle be with you...always"

-----Original Message-----

Sent: Friday, September 21, 2001 4:58 PM To: Multiple recipients of list ORACLE-L

Christopher,

Thanks for the reply.

Surrogate key solves the problem of having a record with a unique identifier for a record. But I still have the following problems.

How do I link the previous records whenever a query is issued by the user?
Please see my requirement below:

Scenario:

User inserts a record into transaction table. In the first record, Account ID value is "HP" and he might insert a record into the child table (Or this transaction may not insert a record into a child table). After some time, the user queries the original record with the primary key and then changes the value in the column - Account ID to "IBM". Now, the original transaction record is NOT UPDATED. A record IS INSERTED with the new values. Also, he might or might not insert a record into a child table with this new values of primary key.

Now the user would query the transaction table with Account ID = IBM. But, the user wants to get all the previous records also; in this case, he want to see the record with Account ID = "HP" also. Also, he want to see the related records from the child tables.

How do I do this?

Thanks,

Rao

-----Original Message-----
Sent: Friday, September 21, 2001 3:17 PM To: Multiple recipients of list ORACLE-L

Then use a surrogate key, i.e. sequence number.

Numbers that change are not candidates for key, doing so introduces problems in which you are having as well as others. "Do not criticize someone until you walked a mile in their shoes, that way when you criticize them, you are a mile a way and have their shoes." Christopher R. Spence
Oracle DBA
Phone: (978) 322-5744
Fax: (707) 885-2275
Fuelspot
73 Princeton Street
North, Chelmsford 01863

-----Original Message-----

Sent: Friday, September 21, 2001 2:30 PM To: Multiple recipients of list ORACLE-L

In our case, we do not have any other columns --- 1. which could identify uniquely a record and yet do not undergo a change.

Thanks,

Rao
-----Original Message-----

Sent: Friday, September 21, 2001 1:35 PM To: Multiple recipients of list ORACLE-L Generally it is bad practice to use columns in the primary key, which change. They introduce many different problems.

"Do not criticize someone until you walked a mile in their shoes, that way when you criticize them, you are a mile a way and have their shoes." Christopher R. Spence
Oracle DBA
Phone: (978) 322-5744
Fax: (707) 885-2275
Fuelspot
73 Princeton Street
North, Chelmsford 01863

-----Original Message-----

Sent: Friday, September 21, 2001 12:35 PM To: Multiple recipients of list ORACLE-L

List,

OLTP application with 24x7 requirement. 300,000 records per day are inserted into the transaction table. Environment: Solari 7. Oracle 817.

The transaction table layout.

Security ID
Account ID
Account Type
Trade Date
And other columns in this table.

In the above table, the primary key is -- Security ID + Account ID + Account Type + Trade Date

There are many to one relationships built to other child tables from Transaction Table

Scenario:

I tried with the idea of sequence number generation but it was failing.

Any ideas or suggestions are much appreciated.

Thanks,

Rao
Maheswara Rao,
Oracle DBA
SunGard Securities

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Author: Rao, Maheswara
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