Army wrote:
> Daniel John Debrunner wrote:
>
>>
>> I'm suprised this is not documented, BLOB and CLOB columns do not work
>> with triggers. This is because within the database engine, there is no
>> mechanism to create a java.sql.Blob object (or Clob) from a SQL BLOB
>> (CLOB) datatype. The java.sql.Blob returned from a ResultSet is handled
>> at the JDBC layer, not within the engine. This is the same reason as to
>> why BLOB and CLOB types cannot be passed into a method or function.
>
>
> 1) Does this mean that we don't support _any_ triggers that are defined
> on tables having lob columns? Or is there some qualifier to that?
Sorry, I think the qualifier should have been: accessing LOB columns of
the modified table by the action statement is not supported.
> 2) If we don't support this, should there be code to catch this scenario
> and print out a more friendly error message? The existing error ("An
> attempt was made to put a data value of type
> 'org.apache.derby.impl.jdbc.EmbedBlob' into a data value of type
> 'BLOB'") isn't altogether intuitive.
That would be one approach.
>
> 3) Should I change this to a documentation error, then?
There are really three issues:
- document the current restrictions
- with the current restriction produce a better error message
- implement LOB support in the referenced tables.
Dan.
