Many projects need addition of identical columns to all the tables created by the project. Audit columns are an example of such a requirement. The requirement is to add columns such as created_by, created_date, modified_by and modified_date to all the tables, these columns store, who created the row, when the row was created, who modified the row last and when was it modified. created_by and created_date are required to be present when the row is inserted and thus are required to be not nullable. Adding these columns to each and every table is a lot of work for developers.
Behavior Driven Database Development
Asserting behavior of the database just like software
When Behavior Driven Development BDD was introduced, some of the key principles were
- Requirements are behavior,
- Provides “ubiquitous language” for analysis,
- Acceptance criteria should be executable.
- Design constraints should be made into executable tests.
Migrations in NoSQL databases
In relational database usage the pattern of migrations is well understood and has gained widespread acceptance. Frameworks such as DBDeploy, DBMaintain, MyBatis migrations, Flyway, Liquibase, Active Record Migrations and many others. These tools allow to migrate the database and maintain the version history of the database in the database.
With the rise of NoSQL Databases and their adoption in development teams we are faced with the problem of migrations in NoSQL databases. What are the patterns of data migrations that work in NoSQL databases? as NoSQL databases are schema free and the database does not enforce any schema validation, the schema of the data is in the application and thus allows for different techniques of data migration.
10 node mongodb ReplicaSet on a Single Machine"
While doing evalauation of NoSQL databases, we had a 10 node riak cluster and wanted check how a similar setup would work with mongodb. So started to setup a 10 node mongodb cluster. Since this was for initial spikes, we decided to set this up on a single machine as with the other test setup using Riak.
Before I explain how we setup 10 node mongodb ReplicaSet, let me talk about replica sets. MongoDB implements replication, providing high availability using replica sets. In a replica set, there are two or more nodes participating in an asynchronous master-slave replication. The replica-set nodes elect the master node, or primary node, among themselves and when the primary node goes down, the rest of the node elect the new primary node.
Moved my blog to octopress
Its been about a month since my blog moved to octopress, wanted to write about my experience. I had been running my blog for a some time now using Movable Type upgrading as and when new versions where released. Over time I realized that upgrading was fraught with errors as lot of steps had to be done manually. Customizing the layout was risky as there was no way to preview your changes and commit only when I was comfortable. With the release of Movable Type 6 there is no longer a free version to download.
