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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3033) select query results in nullpointer exception in skipScan()
Date Tue, 25 Sep 2007 04:03:51 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3033?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Bryan Pendleton updated DERBY-3033:
-----------------------------------

    Attachment: repro2.java

I fiddled around with repro2.java, and have attached an updated version.
Manipulating the table sizes and table row statistics in various ways
didn't succeed in convincing the optimizer to choose the join order I wanted.

I re-wrote the query a different way, and then I seemed to get the join
order I wanted, but my query rewrite resulted in re-casting the query
as 2 select nodes with 2 tables each, rather than a single node with 3
tables, and hence the compiler never peformed transitive closure of
the predicates, so that query didn't tickle the bug either.

Drat. I'll sleep on it, and maybe some new ideas will occur.

> 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, 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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