Re: Representation for Deleted Entities: difficult question

You didn't post database you're using.

In Oracle you could partition the main table (from where all 'cascaded' is coming from) into deleted/undeleted records. Put a view on top of the table just as original table would look like with where clause 'undeleted' and the undeleted partition would always be used. Only certain versions of oracle allow rows to migrate from partition to partition, u can look it up.

However, you would still suffer from 'performance' issues on the other tables, if your data is truly huge.

Best solution would probably be to separate all deleted/undeleted data into separate tables, and built a union view on top of them for reporting purposes.

my2c
Someone might have a better idea.

On 13 May 2004 11:32:21 -0700, robertbrown1971_at_yahoo.com (Robert Brown) wrote:

>Our customer (of our ecommerce system) wants to be able to preserve
>deleted entities in the database so that they can do reporting,
>auditing etc.
>
>The system is quite complex where each end user can belong to multiple
>institutional affiliations (which can purchase on behalf of the user).
>The end user also has a rich trail of past transactions affiliations
>etc. Thus in the schema each user entity is related to many others
>which in turn relate to yet others and so on.
>
>In the past when a user was deleted all of his complex relationships
>were also deleted in a cascading fashion. But now the customer wants
>us to add a "deleted" flag to each user so that a user is never
>_really_ deleted but instead his "deleted" flag is set to true. The
>system subsequently behaves as if the user did not exist but the
>customer can still do reports on deleted users.
>
>I pointed out that it is not as simple as that because the user entity
>is related to many, many others so we would have to add this "deleted"
>flag to every relationship and every other entity and thus have
>"deleted" past purchases, "deleted" affiliations - a whole shadow
>schema full of such ghost entities. This would overtime degrade
>performance since now each query in the system has to add a clause:
>"where deleted = 0".
>
>I assume this is a standard problem since many organizations must have
>this need of preserving deleted records (for legal or other reasons).
>I tried to talk them into creating a simple audit file where all the
>deletions will be recorded in XML but they were not too happy with
>that.
>
>Is there a more satisfying solution to this than have this "deleted"
>flag?
>
>Thanks for your help,
>
>- robert

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We use Oracle 8.1.7.4 on Solaris 2.7 boxes remove NSPAM to email Received on Thu May 13 2004 - 21:32:28 CEST