Hibernate version: 3.1.x

When I have a mapped composite-id, e.g.:


and I make a HQL query on a part of the composite-id, such as:


the result is an invalid query:


As you see, even though the mapped composite-id class is backed by individual properties on the T1 class (id and validFrom in this case), the query treats them as a single block and won't generate a query on id alone. It always wants to consider id and validFrom together.

It is not uncommon to make a query on just a part of a composite primary key, but it seems impossible in HQL.

Should this be considered a bug or undesired behaviour? Any workarounds? It makes the mapped composite-id kind of useless in my opinion.

try this



and query :

Alas, that doesn't work:



In a way logical, since mapped="true" means that you don't really have a component but just use the class like a kind of overlay.

remove it and make class

I can't make a class since we're mapping the same class twice here. In one case only the id is primary key, in the other case (for historization purposes) we need a composite key containing both id and validFrom.

The fact that a mapped composite-id works like a kind of overlay appealed to me. However, since the mapped composite-id seems pretty useless as it works, I have thrown it out and now I use a normal composite-id without class (component) at all. It is uglyer, but it works.

So still I'm wondering what a mapped="true" composite-id is for, given the way it works it seems pretty useless to me.

read chapter 5.1.5 composite-id from documentation