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https://issues.apache.org/jira/browse/JENA-294?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13438956#comment-13438956
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Simon Helsen commented on JENA-294:
-----------------------------------
While I agree your version may be "more" conventional, we had clients who
produced the one I provided. Not only that, their "less conventional query" was
generated by a generator so I am sure they had their reasons. Finally, and this
is important to us, they had their queries tested for performance on our
previous adoption of 2.6.x and the move to 2.7.x turned it into a performance
regression for them. As I have mentioned before, we are talking a few 100ms
versus many minutes.
So, in this case, we really need a fix for the query I provided above.
Otherwise, we are still in the same situation as before I opened this defect
(which is why I reopened). More generally, I am not sure why the same "trick"
cannot be applied here. Leave filter as it is and simply push the assignment
down. Why is that unique to OPTIONAL?
As for providing tests for jena-arq/testing/ARQ/OptFilterEquality/, I am happy
to add a test if I have one, but it seems that this test suite is only to check
query correctness not whether the optimization took place, or am I missing
something
> TransformFilterEquality does not handle starting OPTIONAL well
> --------------------------------------------------------------
>
> Key: JENA-294
> URL: https://issues.apache.org/jira/browse/JENA-294
> Project: Apache Jena
> Issue Type: Improvement
> Components: ARQ
> Affects Versions: Jena 2.7.4
> Reporter: Simon Helsen
> Assignee: Andy Seaborne
> Fix For: ARQ 2.9.4
>
> Attachments: jena-294-afs-1.patch, patch.txt, patch.txt,
> test-filter-equality.zip
>
>
> There was one other case where our tests were stuck on a very slow query
> execution because transformFilterEquality failed to optimize. The problem is
> that the optimizer gives up whenever the WHERE clause starts with an OPTIONAL
> clause. The reason is that the generated algebraic formula starts with a
> TableUnit and this is not handled correctly.
> I have attached a patch which fixes the problem
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