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What does setting SubClassFetchMode e.g. to EAGER_PARALLEL actually do?

Why would one want a subclass to have a different FetchMode?

The implementation spec for KODO and OpenJPA is notoriously bad and I can't figure it out.

Neil Stockton
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BestPractices
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  • What is the reason for the downgrade on the question? – BestPractices Apr 14 '10 at 21:31
  • I am asking for an answer to either Kodo OR OpenJPA. Either answer will help me. The two are very much related - "What is the current relationship between Kodo and OpenJPA? Version 4.1 of Kodo will be based on the OpenJPA code base." [http://openjpa.apache.org/faq.html#FAQ-WhatisthecurrentrelationshipbetweenKodoandOpenJPA%253F] – BestPractices Apr 15 '10 at 14:09

1 Answers1

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From http://download.oracle.com/docs/cd/E15523_01/apirefs.1111/e13946/ref_guide_professional_eager.html

"Setting your subclass fetch mode to parallel affects table-per-class and vertical inheritance hierarchies. Under parallel mode, Kodo issues separate selects for each subclass in a table-per-class inheritance hierarchy, rather than UNIONing all subclass tables together as in join mode. This applies to any operation on a table-per-class base class: query, by-id lookup, or relation traversal."

BestPractices
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