Maven and GitHub

 I spent half a day trying to upload my package to GitHub Maven following the guidelines GitHub Maven. As usual, it seemed too good to be true to be successful immediately. Most of the time, I was haunted by a mysterious message which failed mvn deploy command.

RROR] Failed to execute goal org.apache.maven.plugins:maven-deploy-plugin:2.7:deploy (default-deploy) on project RestService: Failed to deploy artifacts: Could not transfer artifact com.restservice:RestService:jar:1.0-20210228.194713-1 from/to github (https://maven.pkg.github.com/stanislawbartkowski/RestService): Failed to transfer file: https://maven.pkg.github.com/stanislawbartkowski/RestService/com/restservice/RestService/1.0-SNAPSHOT/RestService-1.0-20210228.194713-1.jar. Return code is: 422, ReasonPhrase: Unprocessable Entity. -> [Help 1]

After several hours I was at the point of giving up. The salvation came from stackoverflow.

Could you try lower casing your artifact ID

It was the point,  "Return code is: 422, ReasonPhrase: Unprocessable Entity" translates as "use lower case".

Wrong:

<artifactId>RestService</artifactId>

Correct:

 <artifactId>restservice</artifactId>

Java, Parquet and JDBC

 That is strange but it is almost impossible to access Parquet files outside Hadoop/Spark context. I was trying to move data imprisoned in Parquet to JDBC accessed relational database using standalone Java application and failed.

So I ended up with Spark/Java application to address the issue. 

Source and description: https://github.com/stanislawbartkowski/ParquetJDBC

The application loads Parquet formatted data, it can be a single file or a directory, partition the data into several chunks, launches executors and loads data into JDBC databases in parallel. The number of partitions and executors are configurable. 

The application was tested as a local and single-node Spark configuration. The next step is to configure and test the application in a distributed Hadoop environment.