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HHH-11442 - Update documentation for HHH-10858

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Vlad Mihalcea 2017-02-02 14:11:53 +02:00
parent ce95ffe441
commit a4125ad28e
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documentation/src/main/asciidoc/userguide/chapters/domain/basic_types.adoc
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@ -1056,6 +1056,24 @@ include::{extrasdir}/basic/basic-jpa-convert-period-string-converter-sql-example
----
====
[[basic-jpa-convert-type]]
===== `AttributeConverter` Java and JDBC types
In cases when the Java type specified for the "database side" of the conversion (the second `AttributeConverter` bind parameter) is not known,
Hibernate will fallback to a `java.io.Serializable` type.
If the Java type is not know to Hibernate, you will encounter the following message:
> HHH000481: Encountered Java type for which we could not locate a JavaTypeDescriptor and which does not appear to implement equals and/or hashCode.
> This can lead to significant performance problems when performing equality/dirty checking involving this Java type.
> Consider registering a custom JavaTypeDescriptor or at least implementing equals/hashCode.
Whether a Java type is "known" means it has an entry in the `JavaTypeDescriptorRegistry`.
While by default Hibernate loads many JDK types into the `JavaTypeDescriptorRegistry`, an application can also expand the `JavaTypeDescriptorRegistry` by
adding new `JavaTypeDescriptor` entries.
This way, Hibernate will also know how to handle a specific Java Object type at the JDBC level.
[[basic-jpa-convert-mutability]]
===== JPA 2.1 `AttributeConverter` Mutability Plan