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https://issues.apache.org/jira/browse/DERBY-6308?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13725636#comment-13725636
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ASF subversion and git services commented on DERBY-6308:
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Commit 1509000 from [~rhillegas] in branch 'code/trunk'
[ https://svn.apache.org/r1509000 ]
DERBY-6308: Correct type in the license header of OptimizerOverridesTest;
commit derby-6308-01-aa-correctLicenseHeader.diff.
> joinStrategy optimizer override is ignored if you don't also specify joinOrder
> ------------------------------------------------------------------------------
>
> Key: DERBY-6308
> URL: https://issues.apache.org/jira/browse/DERBY-6308
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.11.0.0
> Reporter: Rick Hillegas
> Attachments: derby-6308-01-aa-correctLicenseHeader.diff,
> DERBY_6308.java
>
>
> Using the schema from OptimizerOverridesTest, the following query...
> select * from --DERBY-PROPERTIES joinOrder=FIXED
> t1 a, t1 b --DERBY-PROPERTIES joinStrategy=NESTEDLOOP
> where a.c1 = b.c1
> ...correctly produces this plan: ( T1_C1C2C3 * T1_C1C2C3 )
> However, if you omit the joinOrder directive, the resulting query...
> select * from
> t1 a, t1 b --DERBY-PROPERTIES joinStrategy=NESTEDLOOP
> where a.c1 = b.c1
> ...unexpectedly produces a hash join order: ( T1_C1C2C3 # T1_C1C2C3 )
> The Tuning Guide says that you should specify the joinOrder directive in
> order to get optimal results, but the Tuning Guide does not indicate that the
> joinOrder directive is required in order to activate the joinStrategy
> directive. See the Tuning Guide section titled "Overriding the default
> optimizer behavior".
> Is this behavior expected? If so, should we change the Tuning Guide to say
> that the joinOrder directive is required in order to activate the
> joinStrategy directive?
> For reference, here is the same query with a new-style optimizer plan
> override...
> select * from t1 a, t1 b where a.c1 = b.c1--derbyplan ( T1_C1C2C3 *
> T1_C1C2C3 )
> ...which produces the expected plan: ( T1_C1C2C3 * T1_C1C2C3 )
> I will attach a repro.
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