NHibernate Performance Object Relational Mapper For .Net

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NHibernate PerformanceObject Relational
MapperFor .Net

• Oren Eini
• Orene_at_we-can.co.il

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Eager Fetching

• Using HQL
• from Blog blog left join fetch blog.Posts
• where user in elements(blog.Users)
• Left / inner joins are supported.
• Using Criteria API
• SetFetchMode(Orders, FetchMode.Eager)
• outer-jointrue
• max fetch depth
• Only one collection, but multiple references.

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Batch Fetching

• Loads other objects associations.
• 100 Blog objects in memory, access one Blogs
  Posts collection, loads for the first 10 objects.
• batch-size10
• On classes
• On associations

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Caching

• Session Cache Called First Level Cache. Cache
  the instances of the objects.
• Session Factory Cache Called Second Level
  Cache. Cache the individual values, relationships
  do not stale.
• Requires adding ltcache usage'read-onlyread-write
  nonstrict-read-write'/gt to the mapping of the
  class.
• Requires adding the same tag to any association
  as well.
• Can define regions for queries.
• Session.CreateQuery(from Blog blog where
  blog.Blogger blogger).SetEntity(blogger,blo
  gger).SetMaxResults(15) .SetCacheable(true).SetCa
  cheRegion(foo).List()
• Cache regions can be configured independantly.

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Miscellaneous Tips

• dynamic-updatetrue, dynamic-inserttrue
• useful in some cases, if the object has a large
  column.
• Prefer not to use, since it means that the server
  cant cache plans as easily.
• Can set a reference (property) to lazy, and it
  will be loaded on demand.
• Accessing the Primary Key of an object will never
  cause a database call.

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Questions Comments
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