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Become the nhibernate Guru - PowerPoint PPT Presentation
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Become the nhibernate Guru. Torkel Ödegaard. torkel.odegaard@gmail.com. www.codinginstinct.com. Nhibernate?. ORM (Object-Relational Mapper). Transparent persistance. Persistence ignorance. Become the Guru. Identity map (L1 Cache) Unit Of Work (Session Flush) Cascading
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Presentation Transcript
Become the Guru
- Identity map (L1 Cache)
- Unit Of Work (Session Flush)
- Cascading
- Attached / Detached
- Proxy / Lazy loading
- ID generation / unsaved-value
- Concurrency
- Legacy databases
- Performance
unit of work
session.Flush()
Flush Mode
- Auto
- Commit
- Never
- Unspecified
Transaction
Unit Of Work
identity map
An identity map is a database access design pattern
used to improve performance by providing a context-specific
in-memory cache to prevent duplicate retrieval of the same
object data from the database.
identity map
True
identity map
True
identity map - Problems
NHibernate.NonUniqueObjectException
A different object with the same identifier value was already associated with the session
Two instances with same id
identity map - Problems
NHibernate.HibernateException
Identifier of an instance of TieFighter was altered …
cascading
- None
- Save-update
- Delete
- Delete-orphan
- All
- All-delete-orphan
Cascade & Save-update
Transient (unsaved) instance
Transient (unsaved) instance
INSERT INTO Pilot ....
INSERT INTO TieFighter ...
Cascade & none
Transient (unsaved) instance
Transient (unsaved) instance
NHibernate.TransientObjectException
Object references an unsaved transient instance -save the transient instance before flushing
Cascade & none
UPDATE Pilot ....
legacy
- Composite primary keys
- Relations on non-primary keys
- Join
- SQL Queries
- DB Generated fields
performance
- Batching
- Eager loading (eliminate N+1)
- Query Cache
- L2 Cache
i could go on an on...
- NHibernate = endless number of features
resources
- http://nhforge.org/
- http://ayende.com/blog
- http://www.codinginstinct.com
- http://sharparchitecture.net/
Torkel.odegaard@gmail.com
http://tlo.googlecode.com/svn/trunk/presentations/nhibernate_elevate
