How do I query UUIDs stored as binary in a database (JPA/Hibernate/MySQL)

Question

I have a Java/JPA/Hibernate/MySQL based app. I want to use UUIDs for object identity, however I want to ensure database performance does not suffer.

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Answer 1

As long as you already have the ID in binary format, querying it is simple:

byte[] id = ....;
em.createQuery(“SELECT x FROM TableName x WHERE x.id = ?1″, TableName.class).setParameter(1, id).getSingleResult();

Actually if you are just looking up by primary key you can use

em.find(TableName.class, id);

Getting the ID in binary format can be a bit of a pain, especially if you need to be passing it around in URLs etc. I recommend Base64 encoding / decoding it; Apache Commons Codec has helper methods from going from byte[] to URL-safe string and then back to byte[]