[jira] Commented: (DERBY-3033) select query results in nullpointer exception in skipScan()

[Kathey Marsden (JIRA)]

    [ 
https://issues.apache.org/jira/browse/DERBY-3033?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12527266
 ] 

Kathey Marsden commented on DERBY-3033:
---------------------------------------

In BaseActivation I see

protected final DataValueDescriptor getColumnFromRow(int rsNumber, int colId)
                throws StandardException {

        if( row[rsNumber] == null)
        {
            /* This actually happens. NoPutResultSetImpl.clearOrderableCache 
attempts to prefetch invariant values
             * into a cache. This fails in some deeply nested joins. See Beetle 
4736 and 4880.
             */
            return null;
        }
                return row[rsNumber].getColumn(colId);
        }

I am not sure why prefetching invariant values would cause them to be null, but 
looks like a good lead.




> 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
>         Attachments: d3033-sane-ij-session-10.3.1.5.txt, query_plan.new, 
> query_plan.old, 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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