Evolving Databases in Agile Umar Akhter & Rohith Rajagopal

Good DB Management Principles Provide each developer with his/her own DB instance This allows developers to try things out without affecting other developers Sometimes a developer might want 2 instances - one for testing and another for development

Provide each developer with his/her own DB instance

This allows developers to try things out without affecting other developers

Sometimes a developer might want 2 instances - one for testing and another for development

Good DB Management Principles Don't use binary db dumps Because they are hard to version control/merge Use scripts to create the DB schema So a new dev can easily recreate the schema

Don't use binary db dumps

Because they are hard to version control/merge

Use scripts to create the DB schema

So a new dev can easily recreate the schema

Good DB Management Principles Version control the scripts used to create/change the DB schema To keep the DB schema in sync with the code which uses it Automate running the scripts which create the schema Because you will need to create the schema multiple times and you should automate repetitive tasks. Use bat file or ant file

Version control the scripts used to create/change the DB schema

To keep the DB schema in sync with the code which uses it

Automate running the scripts which create the schema

Because you will need to create the schema multiple times and you should automate repetitive tasks.

Use bat file or ant file

Good DB Management Principles Use alter scripts rather than drop table and recreate (or hbm2ddl) both drop table/recreate and hbm2ddl will delete existing data Don't hardcode the paths while automating It's easier to move across machines if the paths are in one place (property file, environment variables)

Use alter scripts rather than drop table and recreate (or hbm2ddl)

both drop table/recreate and hbm2ddl will delete existing data

Don't hardcode the paths while automating

It's easier to move across machines if the paths are in one place (property file, environment variables)

Good DB Management Principles Make sure your tests are easily repeatable You should be able to run your tests any number of times without manual intervention in between Make your tests clean up after each run Make sure your scripts are repeatable You shouldn't need any manual steps to figure out which script to run to get your DB schema right You should be able to invoke the same command which (irrespective of the current state of the DB) will upgrade you to the correct version of the schema

Make sure your tests are easily repeatable

You should be able to run your tests any number of times without manual intervention in between

Make your tests clean up after each run

Make sure your scripts are repeatable

You shouldn't need any manual steps to figure out which script to run to get your DB schema right

You should be able to invoke the same command which (irrespective of the current state of the DB) will upgrade you to the correct version of the schema

Good DB Management Principles Use a tool like DB Deploy which Keeps track of applied alter version in the DB figures out from the schema + the alter files which alters to apply Upgrading production databases becomes very easy Reduced testing overhead for upgrade scripts Deployment becomes easy and fast!!

Use a tool like DB Deploy which

Keeps track of applied alter version in the DB

figures out from the schema + the alter files which alters to apply

Upgrading production databases becomes very easy

Reduced testing overhead for upgrade scripts

Deployment becomes easy and fast!!

Further Reading http://martinfowler.com/articles/evodb.html http://databaserefactoring.com/ http://goforthandcode.blogspot.com/2007/12/brief-history-of-database.html http://goforthandcode.blogspot.com/2008/01/schema-to-survive-winds-of-change.html

http://martinfowler.com/articles/evodb.html

http://databaserefactoring.com/

http://goforthandcode.blogspot.com/2007/12/brief-history-of-database.html

http://goforthandcode.blogspot.com/2008/01/schema-to-survive-winds-of-change.html