# Rails, Oracle and Legacy Schemas

**URL:** <https://www.ruby-forum.com/t/rails-oracle-and-legacy-schemas/92542>\
**Category:** Rails\
**Created:** [April 20, 2007, 3:15pm UTC](https://www.ruby-forum.com/t/rails-oracle-and-legacy-schemas/92542 "2007-04-20T15:15:49Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mfaine](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/b3f665/32.png) [@mfaine](https://www.ruby-forum.com/u/mfaine)\
**Post date:** [April 20, 2007, 3:15pm UTC](https://www.ruby-forum.com/t/rails-oracle-and-legacy-schemas/92542/1 "2007-04-20T15:15:49Z")

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I’m very new to Rails and I’m trying, if only for a proof of concept, to  
develop a quick Rails application to display data from a database. The  
application will be read only (SELECT statements only) and will simply  
list data. However, the table structure and schema I have no control  
over.

It basically breaks down into to tables that both contain attribute  
data. Values that can be repeated are in a table with an \_r at the end  
and values that are always single are in a table with a \_s at the end.  
The tables have a unique identifier row but it is not sequential, and is  
not an autonumber. The data will be routinly updated by an external  
process that will not be related in any way to the rails application.

Here is an idea I had, please let me know if you think it would work.

1. Point rails to a temporary table or view in Oracle.

2. Update this table or view by using a trigger anytime a modification  
to the original table takes place.

Also, I could use some pointers to information on how to manage these  
types of scenarios because if I can do this once I’m sure I will be  
called on to do it again.

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<div class="post-metadata">

**Author:** ![mfaine](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/b3f665/32.png) [@mfaine](https://www.ruby-forum.com/u/mfaine)\
**Post date:** [April 21, 2007, 11:51pm UTC](https://www.ruby-forum.com/t/rails-oracle-and-legacy-schemas/92542/2 "2007-04-21T23:51:01Z")

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If your app is indeed read only, and you _can_ create views, then  
that’s your best bet. Create a view for each table that fits the Rails  
conventions. That way, your Rails application will be just like any  
other.

I don’t know much about Oracle, but if you could create the views in a  
different namespace (schema, etc), then even better, because you get  
to name the views following the Rails conventions for Class ↔ table  
names.

Non-sequential ids should be ok. I believe that all ActiveRecord  
assumes is the existance of a column named ‘id’ on each table, with  
unique integer values. Who knows, maybe they don’t even need to be  
integers.

As far as updating the views with triggers: again, I don’t know about  
Oracle, but in MySQL and PostgreSQL it is possible to create views  
that basically just re-write SQL on the fly. No need to store  
redundant data. And since each one of your views will basically be  
just:

CREATE VIEW widgets AS SELECT foo\_r as foo, bar\_s as bar,  
some\_primary\_key as id from oddly\_named\_table

Then you shouldn’t have much performance problems. Those views are one  
to one with the tables.

On Apr 20, 9:15 am, Mark F. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)