JPA: One entity mapped to multiple rows, is it possible?

Question

In JPA, can I map an Entity to a table where attributes of the entity are persisted across multiple rows?

Basically, can I map a class like this:

public Document {
    String id;
    String title;
    String author;
    String size;
}

To a table like

CREATE TABLE DOC_METADATA
(
    DOC_ID NUMBER,
    ATTR_NAME VARCHAR,
    ATTR_VALUE VARCHAR
);

With content like

DOC_ID   | ATTR_NAME     | ATTR_VALUE
1          "title"         "Alice in wonderland"
1          "author"        "Lewis Carroll"
1          "size"          "500kb"
2          "title"         "Winnie the pooh"
2          "author"        "A. A. Milne"
2          "size"          "600kb"

Answer 1

No it's impossible. Your class Document is a domain class (java presentation of your table in db). When you try to create table from domain class so will be created a table with such fields like in your domain class.

Answer 2

I think you need to take look at what JPA is. Take a look at

• http://www.programming-simplified.com/jpa_video_training.html
• http://docs.oracle.com/javaee/7/tutorial/doc/persistence-intro.htm#BNBPZ