11.1.12 DiscriminatorColumn
Annotation
For the SINGLE_TABLE mapping
strategy, and typically also for the JOINED strategy,
the persistence
provider will use a type discriminator column. The DiscriminatorColumn annotation is used to
define the discriminator column for the SINGLE_TABLE
and JOINED inheritance mapping strategies.
and
11.2.2.7
DiscriminatorColumn
A discriminator column is generated
for the SINGLE_TABLE mapping strategy and may
optionally be
generated by the provider for use with the JOINED
inheritance strategy. The DiscriminatorColumn
annotation may be used to control the
mapping of the discriminator column. See section
11.1.12
for the rules that pertain to discriminator columns.
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The discussion I want to initiate is not whether
Eclipselink is wrong to require this (clearly it’s not
given the Spec’s language), but whether Eclipselink
should be enhanced to permit its absence in the interest
of making migration from these other providers to
Eclipselink easier, and to gauge developer community
support for this enhancement.