Eager fetch problem with map collections

[Harald Wellmann]

I have an entity with a map collection, and I'm trying to select a list of
these entities with an eager fetch for the map collection. 

I read about OpenJPA's Eager Fetch Modes NONE, PARALLEL and JOIN, and I've
experimented with various global or per-query settings, but I'm always
getting the NONE behaviour with 1+n selects, instead of the expected 1+1
selects for PARALLEL or a single select for JOIN.

Could it be that the JOIN mode is not yet supported for maps (I'm using
OpenJPA 2.0.1)? Or am I overlooking anything?

Here is my entity:

@Entity
class OsmNode
{
    @Id
    private long id;

    private int longitude;
    private int latitude;

    @ElementCollection(fetch = FetchType.EAGER)
    @MapKeyColumn(name = "k")
    @Column(name = "v")
    @CollectionTable(name = "node_tags", joinColumns = @JoinColumn(name =
"id"))
    private Map<String, String> tags;
}

The JPQL query is

select n from OsmNode n join fetch n.tags

and even with openjpa.jdbc.EagerFetchMode=join, I'm getting the following
1+n SQL selects:

SELECT t0.id, t0.latitude, t0.longitude FROM osm.nodes t0
SELECT t0.k, t0.v FROM osm.node_tags t0 WHERE t0.id = ?

TIA for any help!

Best regards,
Harald


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