Re: Tracking changes to the schema over time

You could license the change management pack for grid control.  It will give
you schema baselines and allow you to see diffs from those baselines.  So
you could create a baseline called version1 when you were ready to upgrade,
you would run a comparison between current and baseline.  If there are no
diffs, you are good to go otherwise, the changes will need to be reconciled
before the patch is applied.  Once the patch is applied, create a new
baseline called version2.  The rub with this solution is that it does const
extra $$ for the pack.  Logging your patches to a database table is a good
solution also provided the environment is locked down and CM procedures are
followed.  The optimal solution would be to use both of these techniques,
logging the patches to keep you in a known state and diffing the schemas to
check for changes made outside the process.

On 5/3/07, Eric Gross <egross@xxxxxxxxxxx> wrote:


Hello everyone-

I am looking to solve a problem that I hope already has been solved by
some of you.  We have a database schema that changes over time in subtle
ways (a column's datatype changes or a stored procedure changes).  The
version of the schema in use is tightly coupled with the version of the
application in use so as the application is upgraded, so too must the
database schema.  Each version will have a patch SQL script that will
update from the previous version to the current version so I just need
to know the current version and then run all the patches between that
version and the current version.

How can I determine what version of a schema is in use so that I can run
the required scripts to upgrade it to the current version?



Options I have considered:
       * A table with one row per version where you would insert a new
row each upgrade.  The issue with this method is that there is no
guarantee that the version indicated in this table matches up with the
actual schema (perhaps an upgrade broke and didn't do everything it was
supposed to do).
       * I could write a custom script to inspect every aspect of every
object to confirm its version.  This sounds really hard and I can't
think of any way for DBMS_METADATA to help me out.

This is 10gR2.  The objects in question are tables, mviews (and their
snapshots & refresh groups), indexes, functions, and procedures.

Thanks,
e.

Eric Gross
GridApp Systems
Mr. Database
egross@xxxxxxxxxxx
p: (646) 452-4050
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