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alpha137
 Post subject: question: blob versus longblob with SchemaExport and MySQL
PostPosted: Tue Dec 14, 2004 10:24 am 
Newbie

Joined: Fri Feb 20, 2004 7:37 am
Posts: 12
Hibernate version:
2.1.7b

Hi,

I'm using a user type BinaryBlobType to map a blob to a byte[] (as described in http://www.hibernate.org/73.html) and SchemaExport to generate the DDL.

Everything is fine for MS SQL Server - SchemaExport creates an
Code:
image
column for the blob field which has a maximum size of 2GB.

Under MySQL the SchemaExport generates the datatype
Code:
blob
which has a maximum size of only 64KB.
MySQL differentiates between blob (64KB), mediumblob (16MB) and longblob (4GB).

I have seen that the SchemaExport XML-attribute "sql-type" allows overriding of the automatic datatype detection - but I really don't like that.

Shouldn't be
Code:
longblob
the default blob datatype under MySQL? I mean - a blob with a 64KB limit is more a "bob" than a "blob". ;-)
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michael
 Post subject:
PostPosted: Tue Dec 14, 2004 11:35 am 
Hibernate Team
Hibernate Team

Joined: Tue Sep 09, 2003 2:10 pm
Posts: 3246
Location: Passau, Germany
You can write a simple custom Dialect to change that.
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Lukasz (Qr)
 Post subject:
PostPosted: Tue Dec 14, 2004 6:31 pm 
Regular
Regular

Joined: Tue Sep 28, 2004 6:34 pm
Posts: 50
CLOB becomes TEXT 64k but you can define length="16777215" to make it MEDIUMTEXT - I guess you can do the same for blobs:)

Lukasz
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gavin
 Post subject:
PostPosted: Tue Dec 14, 2004 7:56 pm 
Hibernate Team
Hibernate Team

Joined: Tue Aug 26, 2003 12:50 pm
Posts: 5130
Location: Melbourne, Australia
Quote from MySQLDialect.java:

Code:
      registerColumnType( Types.VARBINARY, "longblob" );
      registerColumnType( Types.VARBINARY, 16777215, "mediumblob" );
      registerColumnType( Types.VARBINARY, 65535, "blob" );
      registerColumnType( Types.VARBINARY, 255, "tinyblob" );



Sometimes, it can be worth checking the code ;-)
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