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https://issues.apache.org/jira/browse/DERBY-3033?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12529906
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Bryan Pendleton commented on DERBY-3033:
----------------------------------------
I've succeeded in using the optimizer overrides to force nested loop joins,
and to force the use of the secondary index access paths, but I haven't
yet figured out how to force the join order that I want using the optimizer
overrides.
It's tricky because the optimizer overrides are specified on the query
before it's been flattened, but I want to force a particular join order after
flattening.
> select query results in nullpointer exception in skipScan()
> -----------------------------------------------------------
>
> Key: DERBY-3033
> URL: https://issues.apache.org/jira/browse/DERBY-3033
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.2.2.0
> Environment: Windows XP, Java 5.0, JDBC, Derby 10.2.2.0
> Reporter: Haolan Qin
> Assignee: Bryan Pendleton
> Attachments: bug4736.sql, d3033-sane-ij-session-10.3.1.5.txt,
> generatedActivation.txt, noClosureOfNotExists.diff, query_plan.new,
> query_plan.old, queryPlanRS.txt, repro2.java, test.rar, test.zip,
> viewer_10_1.zip
>
>
> The following error was repeatedly thrown when we tried to run a select query
> via JDBC. Strangely, the exact same select query did not trigger any error
> when run from the command line console. After we added an index, the error
> went away completely.
> java.lang.NullPointerException
> at org.apache.derby.impl.sql.execute.NoPutResultSetImpl.skipScan(Unknown
> Source)
> at org.apache.derby.impl.sql.execute.TableScanResultSet.openCore(Unknown
> Source)
> at
> org.apache.derby.impl.sql.execute.IndexRowToBaseRowResultSet.openCore(Unknown
> Source)
> at
> org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(Unknown
> Source)
> at org.apache.derby.impl.sql.execute.JoinResultSet.openRight(Unknown Source)
> at org.apache.derby.impl.sql.execute.JoinResultSet.openCore(Unknown Source)
> at
> org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(Unknown
> Source)
> at org.apache.derby.impl.sql.execute.SortResultSet.openCore(Unknown Source)
> at
> org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(Unknown
> Source)
> at org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl.open(Unknown
> Source)
> at org.apache.derby.impl.sql.GenericPreparedStatement.execute(Unknown Source)
> at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(Unknown Source)
> at
> org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Unknown
> Source)
> at org.apache.derby.impl.jdbc.EmbedPreparedStatement.execute(Unknown Source)
> at org.apache.derby.impl.drda.DRDAStatement.execute(Unknown Source)
> at org.apache.derby.impl.drda.DRDAConnThread.processCommands(Unknown Source)
> at org.apache.derby.impl.drda.DRDAConnThread.run(Unknown Source)
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