This week's book giveaway is in the OO, Patterns, UML and Refactoring forum.
We're giving away four copies of Five Lines of Code and have Christian Clausen on-line!
See this thread for details.
Win a copy of Five Lines of Code this week in the OO, Patterns, UML and Refactoring forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Bear Bibeault
  • Ron McLeod
  • Jeanne Boyarsky
  • Paul Clapham
Sheriffs:
  • Tim Cooke
  • Liutauras Vilda
  • Junilu Lacar
Saloon Keepers:
  • Tim Moores
  • Stephan van Hulst
  • Tim Holloway
  • fred rosenberger
  • salvin francis
Bartenders:
  • Piet Souris
  • Frits Walraven
  • Carey Brown

hibernate primary key mapping - sequence

 
Greenhorn
Posts: 19
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
in the following xml the sequence is defined (for Oracle DB):

<id name="id" column="PENDING_ORDER_ID"
unsaved-value="-1">
<generator class="native">
<param name="sequence">
UNIQUE_ID_SEQUENCE</param>
</generator>
</id>

but what if the alternative database is MySQL which doesn't have sequences. Then what the hibernate will do in this case? Should i write another MySQL mapping to exclude sequence param from mapping?

regards,
Eugene
 
Bartender
Posts: 10336
Hibernate Eclipse IDE Java
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
You can't use sequences with MySQL, so I presume Hibernate will throw some sort of exception if you try. The sequence generation strategy will only work with those DBs that support sequences (DB2, PostgreSQL, Oracle, SAP, McKoi and Firebird). Its a little gotcha in Hibernate's "one mapping layer for all databases" claim, albeit an understandable and documented one.

However that mapping you posted is a native generation strategy, not a sequence generation stategy. Native will use another generator depending on the database. If its Oracle for example Hibernate will look for a sequence called UNIQUE_ID_SEQUENCE. If its MySQL, it will try to use something else (probably identity - but you'll find that out when you run it against your MySQL schema).
 
Ranch Hand
Posts: 1780
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Why not try it and see what happens?
 
please buy my thing and then I'll have more money:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop
https://coderanch.com/wiki/718759/books/Building-World-Backyard-Paul-Wheaton
    Bookmark Topic Watch Topic
  • New Topic