Querying a service or a database from a Spark job is in most cases an
anti-pattern, but there are exceptions. The jobs become unstable and
indeterministic by relying on a live database.
The recommended pattern is to take regular dumps of the database to
your cluster storage, e.g. HDFS, and join th
Spark has its best use cases in in-memory batch processing / machine learning.
Connecting multiple different sources/destination requires some thinking and
probably more than spark.
Connecting spark to a database makes only in very few cases sense. You will
have huge performance issues due to th
