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https://issues.apache.org/jira/browse/DERBY-3033?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12526825
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Kathey Marsden commented on DERBY-3033:
---------------------------------------
I was wondering in the skipScan code, should the column values of startPosition
ever be null? In this case column[0] is null, but I was wondering if that is
ever expected.
startPosition IndexRow (id=136)
column DataValueDescriptor[1] (id=149)
[0] null
ncols 1
orderedNulls boolean[1] (id=150)
[0] false
Just to try to understand the impact I tried this small change, which
interestingly caused the test case and suiltes.All to pass, but I don't really
understand what it means for the column value to be null.
I am guessing this is not the correct solution but rather there is some sort of
problem in generating the column value for startPosition. Just want to check
though in case there is a circumstance where the column value should be null
and this change is ok.
Index: java/engine/org/apache/derby/impl/sql/execute/NoPutResultSetImpl.java
===================================================================
--- java/engine/org/apache/derby/impl/sql/execute/NoPutResultSetImpl.java
(revision 574932)
+++ java/engine/org/apache/derby/impl/sql/execute/NoPutResultSetImpl.java
(working copy)
@@ -388,7 +388,8 @@
{
if (startKeyLonger)
checkNullCols[cncLen++] = position + 1;
- if (startPosition.getColumn(position +
1).isNull())
+ DataValueDescriptor d = startPosition.getColumn(position +1);
+ if (d == null || d.isNull())
{
returnValue = true;
if (! startKeyLonger)
Thanks for the help. I am certainly out of my element with this code, so
appreciate any help or pointers anyone can offer.
Kathey
> 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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