Support for multi indexes

[RickRainerLudwig]

Currently only single indexes are allowed on types. Relating to compound primary key, but also needed for other purposes, the support multi indexes are needed.

For Titan, using also properties for discriminators, this is essential to support multiple types on one node.

[RickRainerLudwig]

I just recognized, that this ticket somewhat overlaps ticket #82 and that this needs to clarified:

1) Ticket #82 is about querying entities by compound keys, for example the movie stars graph: I want to search for a combination of first and last name. This needs to be done by a kind of "compound primary key". 2) This ticket is about having the possibility to mark multiple properties within the entity as indexed. I want to have these properties marked to check during data store initialization for the presence of these indexes and if they are not present and auto-creation is configured, to create them.

Currently, the @Indexed annotation is used for entity retrieval and also for the indexes. Maybe this should be separated? Like @Id (JPA's primary key annotation) and @Indexed for indexed properties?

[DirkMahler]

First draft of example API is working, please review "com.buschmais.xo.neo4j.test.find.FindByExampleTest" if the proposed concept meets the requirement.

[CrystalMethod]

Do you plan to release different artifacts for java7 vs. java8? Or what is the recommended procedure to include src/main/java7/* vs src/main/java8/*? My IDE complains about duplicated class Example.java

[DirkMahler]

The "find by example" feature is targeted to lambda expressions of Java 8 - therefore it will be necessary to provide different artifacts. I see that the current approach has some disadvantages

• IDE support as you mentioned
  • deployment issues during release as two builds (JDK7 and JDK8) are required but both will try to deploy the same stable artifacts to the Sonatype staging repository - this will probably fail

I'm currently thinking of one build using Java 8 and retrolambda to convert classes to language specification level 1.7 for attaching them with a dediated classifier. This would only hold for the XO core artifacts, i.e. xo.api, xo.spi and xo.impl - datastore may stick to Java 7.