Hi Michael,
On May 24, 2011, at 8:43 PM, Michael Hast wrote:
Hi:
We had an interesting problem today. We have an entity called ReviewerData which has a personId and fiscalYear compound primary key. It also has 3 more attributes, a CLOB field, a varchar2(4000) and an Integer attribute. All attributes except the CLOB are marked as a locking attribute (see attached image).
When we are updating the CLOB field and any of the other 2 attributes and call EC saveChanges, we are getting the error:
Expected a LOB count of 0 but could not fetch that many objects.
The issues is that there are 2 SQL statements being generated by the Oracle plugin within 1 transaction:
UPDATE REVIEWER_DATA SET HAS_DONE_EXTERNAL_REVIEW = ?, REVIEW_QUALIFICATIONS = EMPTY_CLOB() WHERE (PERSON_ID = ? AND FISCAL_YEAR = ? AND DESCRIPTION_OF_WORK = ? AND HAS_DONE_EXTERNAL_REVIEW = ?) withBindings: 1:0, 2:97208, 3:2012, 4:"ABC", 5:1
SELECT t0.REVIEW_QUALIFICATIONS FROM REVIEWER_DATA t0 WHERE (t0.PERSON_ID = ? AND t0.FISCAL_YEAR = ? AND t0.DESCRIPTION_OF_WORK = ? AND t0.HAS_DONE_EXTERNAL_REVIEW = ?) FOR UPDATE withBindings: 1:97208, 2:2012, 3:"ABC", 4:1
When you see "SELECT ... FOR UPDATE" that is often a sign that something has gone wrong in EOF (e.g. you have hit a bug). In this case, however, I think it is just trying to update the CLOB.
The SELECT statement fails, causing the error above. If I don't have a compound PK, only have a single PK attribute (personId), the SELECT statement only has one column in the where clause and all works great:
SELECT t0.REVIEW_QUALIFICATIONS FROM REVIEWER_DATA t0 WHERE (t0.PERSON_ID = ?) FOR UPDATE withBindings: 1:97208
I believe there is a bug in how the SQL is being generated. In the where clause it should only use the 2 PK attributes rather than all the lock attributes.
My question is how can I fix this? Is it the Oracle plugin? Wonder has an Oracle plugin, should I try that out first?
I would try that first. Second, you could move REVIEW_QUALIFICATIONS to its own table with a generated PK and a 1-1 relationship from Reviewer Data. There is a good chance that would avoid the problem.
Chuck
--
Chuck Hill Senior Consultant / VP Development
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