Let me answer step by step. 1. When do you need ` insertable = false, updatable = false`? Let’s look at the below mapping, public class Zip { @ManyToOne @JoinColumn(name = “country_code”, referencedColumnName = “iso_code”) private Country country = null @Column(name = “country_code”) private String countryCode; } Here we are referring to the same column … Read more
If you set the delete rule to “nullify” and delete the A object, then the references to that object in the Bs will be removed. The inverse works the same way. If you have cascade and delete B then it will remove the A that B pointed to. It will then follow the delete rule … Read more
We have a social graph in which in a day we add almost 1 millions of node and twice as many edges. We started with neo4j graph because yes, it is very fast due to fact that its storage is on the same machine on which graph engine runs. But following are the experiences that … Read more
This all turned out to be because of the way I’ve set SQLAlchemy up in Pyramid. Essentially you need to follow this section to the letter and make sure you use the same declarative_base instance as the base class for each model. I was also not binding a database engine to my DBSession which doesn’t … Read more
You can just remove the entire graph directory with rm -rf, because Neo4j is not storing anything outside that: rm -rf data/* Also, you can of course iterate through all nodes and delete their relationships and the nodes themselves, but that might be too costly just for testing …