add discrete headings to section on compositional basic types
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@ -726,6 +726,7 @@ BitSet bitset;
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All this is nice, but it probably won't surprise you that Hibernate goes beyond what is required by JPA.
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[[compositional-basic-types]]
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=== Compositional basic types
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Hibernate considers a "basic type" to be formed by the marriage of two objects:
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@ -733,8 +734,13 @@ Hibernate considers a "basic type" to be formed by the marriage of two objects:
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- a `JavaType`, which models the semantics of a certain Java class, and
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- a `JdbcType`, representing a SQL type which is understood by JDBC.
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When mapping a basic attribute, we may explicitly specify a `JavaType`, a `JdbcType`, or both.
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[discrete]
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==== JavaType
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An instance of `org.hibernate.type.descriptor.java.JavaType` represents a particular Java class.
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It is able to:
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It's able to:
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- compare instances of the class to determine if an attribute of that class type is dirty (modified),
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- produce a useful hash code for an instance of the class,
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@ -761,6 +767,9 @@ BitSet bitSet;
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Alternatively, the `@JavaTypeRegistration` annotation may be used to register `BitSetJavaType` as the default `JavaType` for `BitSet`.
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[discrete]
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==== JdbcType
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A `org.hibernate.type.descriptor.jdbc.JdbcType` is able to read and write a single Java type from and to JDBC.
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For example, `VarcharJdbcType` takes care of:
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@ -798,6 +807,9 @@ Since Hibernate understand more SQL types than JDBC, there's an extended list of
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For example, `SqlTypes.GEOMETRY` represents the spatial data type `GEOMETRY`.
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****
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[discrete]
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==== AttributeConverter
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If a given `JavaType` doesn't know how to convert its instances to the type required by its partner `JdbcType`, we must help it out by providing a JPA `AttributeConverter` to perform the conversion.
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For example, to form a basic type using `LongJavaType` and `TimestampJdbcType`, we would provide an `AttributeConverter<Long,Timestamp>`.
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