[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-2614) Blob Length Set to 255 By Default With Derby DB

[Jeff Jensen (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2614?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=42392#action_42392 ] 

Jeff Jensen commented on HHH-2614:
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Just encountered this problem too.  With supporting multiple databases, having to determine a legitimate single value for all databases is not desirable.  Different databases can have different max values.  Our preference is to use the database applicable value, i.e. the default.  Of course, this breaks with Derby.

Mike's custom dialect seems the best approach to try workaround this problem (and Strong Liu: we don't want to set a length!).

> Blob Length Set to 255 By Default With Derby DB
> -----------------------------------------------
>
>                 Key: HHH-2614
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2614
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.2.3
>         Environment: Apache Derby 10.2.2, Java 1.6.0
>            Reporter: Sean Sylvis
>            Assignee: Strong Liu
>
> When the (Hibernate) type "blob" is used in an object mapping file and a length is not specified, Hibernate converts this type as "blob (255)" to the Apache Derby database table definition. (This seems to be the same as the conversion behavior of a Java String to "varchar (255).") The same behavior results when using a CustomType that returns a Java SQL Types.BLOB. This is not the behavior I expected.
> Hibernate converts the same type as simply "blob" (which has a maximum length of 65535 bytes when no length is specified) when using MySQL version 5.0 (http://dev.mysql.com/doc/refman/5.0/en/storage-requirements.html). Furthermore, the Derby specification (http://db.apache.org/derby/docs/10.2/ref/rrefblob.html) states that a blob type without a length value will default to a length of 2M-1 bytes.
> I could not find a length specification for the Java SQL Blob type (http://java.sun.com/javase/6/docs/api/), but the current default length does seem to conform to other Hibernate type standards. That is, if a length is not specified, the length defaults to the maximum length defined for that type by the database.

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