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From Army <qoz...@sbcglobal.net>
Subject Re: [jira] Created: (DERBY-438) Update triggers on tables with blob columns fail at execution time if the triggered-SQL-statement references the blob column(s).
Date Sat, 02 Jul 2005 01:02:17 GMT
Daniel John Debrunner wrote:
> Army wrote:
>>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.

So then in the case of a blob column larger than 32K bytes, where we get an 
error even if the action statement doesn't reference/access the lob, that would 
still be a bug, I guess?

ERROR XCL30: An IOException was thrown when reading a 'BLOB' from an InputStream.
ERROR XJ001: Java exception: ': java.io.EOFException'.

Note that this only happens with blob columns, not clobs (don't know why, but it 
probably has something to do with the streaming (or lack of streaming) of 
clobs), and it only happens if the blob is larger than 32K (which is, I think, 
the point at which Derby starts streaming the data).

>>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.

And based on what I wrote above, there'd be a 4th:

- Fix triggers so that they work if the triggered-SQL-statement does NOT 
reference a blob column, even if the blob data in the table is greater than 32K 
bytes long.

Thanks for the input,
Army


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