Hi, I am new to Jena programming.
I am using Jena's SPARQL API to process the query and translate the query into accessing our custom back-end storage. I am now familiar with basic code like subclassing the GraphBase and QueryIter with my own implementation. But I need to learn more on extending the query optimization. I found this doc (http://jena.apache.org/documentation/query/arq-query-eval.html) is a good start, but it's not comprehensive enough for beginner like me. Even the Java API doc also doesn't have much info, for example I was looking at OpExecutorFactory class at https://jena.apache.org/documentation/javadoc/arq/org/apache/jena/sparql/engine/main/OpExecutorFactory.html <https://jena.apache.org/documentation/javadoc/arq/org/apache/jena/sparql/engine/main/OpExecutorFactory.html>One option is to read the Jena source code and try to understand what it does, but it'd be nice if there are some documentation which I can read first before I have to look at the source code. Thanks, Z
