Lots of time hand coded SQL is written in the applications for performance sake, getting data using complex SQL out of the tables. As the database structure changes it becomes really hard to find out all the SQL that needs to be changed. In other cases SQL is generated based on certain conditions in the code and its hard to find if the generated SQL is valid after database changes are done.
Publish data models in CI Pipeline
Enable wider usage of data models by publishing the latest models on team Wikis
Many a times ER models are created by the data team and are not shared outside of the data team generally for the lack of tools licenses, since its not feasible for the entire team to purchase licenses for the ER modelling tools such as Erwin Data Modeller or Er Studio
Using liquibase to load data and ignore some columns
Loading data into tables is needed many times on projects to load test, Liquibase provides a method to load data into tables with lots of customization. In the example shown below, I’m loading zip code data with the following column layout
"Zipcode","ZipCodeType","City","State","LocationType","Lat","Long","Location","Decommisioned","TaxReturnsFiled","EstimatedPopulation","TotalWages"
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.
