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https://issues.apache.org/jira/browse/DERBY-6786?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14284548#comment-14284548
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Mamta A. Satoor commented on DERBY-6786:
----------------------------------------
I have been debugging this issue a little bit and what I have found so far in
the case with INSERT and in the case with no INSERT is that the case with
INSERT goes through additional cycle of binding of the SELECT clause.
Here are the two cases
1)With INSERT
insert into t
select erg.* from (
select d2.s from (select k,s from k1) as d1
left join (select k,s from k2) as d2 on d1.k=d2.k
) as erg
where s > 10;
2)Without INSERT
select erg.* from (
select d2.s from (select k,s from k1) as d1
left join (select k,s from k2) as d2 on d1.k=d2.k
) as erg
where s > 10;
In both of the cases above, first we go through the bind phase of SELECT
erg.*... first.
1)In case with INSERT, here is the code path for the first round of binding of
SELECT erg,*...
SelectNode.bindNonVTITables(DataDictionary, FromList) line: 490
InsertNode(DMLStatementNode).bindTables(DataDictionary) line: 190
InsertNode(DMLStatementNode).bindResultSetsWithTables(DataDictionary) line: 162
InsertNode.bindStatement() line: 246
GenericStatement.prepMinion(LanguageConnectionContext, boolean, Object[],
SchemaDescriptor, boolean) line: 401
GenericStatement.prepare(LanguageConnectionContext, boolean) line: 99
.....
2)In case of no INSERT sql, here is the code path for the binding of SELECT
erg,*...
CursorNode.bindStatement() line: 283
GenericStatement.prepMinion(LanguageConnectionContext, boolean, Object[],
SchemaDescriptor, boolean) line: 401
GenericStatement.prepare(LanguageConnectionContext, boolean) line: 99
At the end of this, the query nodes for the two queries seem to be in sync.
But, for the case with INSERT, we go through the bind phase of SELECT erg.*
again through the following codepath
SelectNode.bindExpressions(FromList) line: 523
InsertNode(DMLStatementNode).bindExpressions() line: 209
InsertNode.bindStatement() line: 338
GenericStatement.prepMinion(LanguageConnectionContext, boolean, Object[],
SchemaDescriptor, boolean) line: 401
GenericStatement.prepare(LanguageConnectionContext, boolean) line: 99
There is following comment before this second round of binding in
InsertNode.bindStatement()
/* Bind the expressions now that the result columns are bound
* NOTE: This will be the 2nd time for those underlying
ResultSets
* that have tables (no harm done), but it is necessary for
those
* that do not have tables. It's too hard/not work the effort
to
* avoid the redundancy.
*/
It is in this second phase of rounding, it looks like we bind the columns to
incorrect position. More work is needed to pin point where exactly the column
mapping is going wrong.
> NullPointerException in INSERT INTO statement with multiple subselects
> ----------------------------------------------------------------------
>
> Key: DERBY-6786
> URL: https://issues.apache.org/jira/browse/DERBY-6786
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.2.2.0, 10.5.1.1, 10.8.2.2, 10.9.1.0, 10.10.1.1,
> 10.11.1.1
> Environment: not relevant, but tested under Windows 7 32bit, Windows
> Server 2008 64bit, Java 6 and Java 7.
> Reporter: Johannes Stadler
> Labels: NullPointerException
> Attachments: acaaeec04ex014axaa2ex076bx000000c72a081.java, repro.sql
>
>
> Hello,
> I'm getting this wrapped NullPointerException when I try to execute an INSERT
> INTO SQL statement:
> java.sql.SQLException: The exception 'java.lang.NullPointerException' was
> thrown while evaluating an expression.
> at
> org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(SQLExceptionFactory40.java:101)
> at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Util.java:148)
> at org.apache.derby.impl.jdbc.Util.seeNextException(Util.java:349)
> at
> org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(TransactionResourceImpl.java:431)
> at
> org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(TransactionResourceImpl.java:353)
> at
> org.apache.derby.impl.jdbc.EmbedConnection.handleException(EmbedConnection.java:2400)
> at
> org.apache.derby.impl.jdbc.ConnectionChild.handleException(ConnectionChild.java:85)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(EmbedStatement.java:1437)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.execute(EmbedStatement.java:711)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.executeLargeUpdate(EmbedStatement.java:190)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.executeUpdate(EmbedStatement.java:179)
> at
> de.foconis.dakobp.unittests.div.TestMain.testNullpointer(TestMain.java:49)
> at de.foconis.dakobp.unittests.div.TestMain.main(TestMain.java:28)
> Caused by: java.sql.SQLException: The exception
> 'java.lang.NullPointerException' was thrown while evaluating an expression.
> at
> org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(SQLExceptionFactory.java:42)
> at
> org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(SQLExceptionFactory40.java:125)
> at
> org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(SQLExceptionFactory40.java:71)
> ... 12 more
> Caused by: java.sql.SQLException: Java exception: ':
> java.lang.NullPointerException'.
> at
> org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(SQLExceptionFactory.java:42)
> at
> org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(SQLExceptionFactory40.java:125)
> at
> org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(SQLExceptionFactory40.java:71)
> at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Util.java:148)
> at org.apache.derby.impl.jdbc.Util.javaException(Util.java:370)
> at
> org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(TransactionResourceImpl.java:436)
> ... 10 more
> Caused by: java.lang.NullPointerException
> at
> org.apache.derby.exe.acf81e0010x014axa9c2x46e6x000000c6dc781.e2(Unknown
> Source)
> at
> org.apache.derby.impl.services.reflect.DirectCall.invoke(ReflectGeneratedClass.java:105)
> at
> org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.getNextRowCore(ProjectRestrictResultSet.java:275)
> at
> org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.getNextRowCore(ProjectRestrictResultSet.java:263)
> at
> org.apache.derby.impl.sql.execute.DMLWriteResultSet.getNextRowCore(DMLWriteResultSet.java:127)
> at
> org.apache.derby.impl.sql.execute.InsertResultSet.open(InsertResultSet.java:519)
> at
> org.apache.derby.impl.sql.GenericPreparedStatement.executeStmt(GenericPreparedStatement.java:461)
> at
> org.apache.derby.impl.sql.GenericPreparedStatement.execute(GenericPreparedStatement.java:340)
> at
> org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(EmbedStatement.java:1344)
> ... 5 more
> Most likely this bug has already been reported as DERBY-5041, which has
> already been closed (although I don't use a GROUP BY clause).
> The original statement is quite complex and partially generated, but the
> error can be reproduced easily, using a statement as simple as this:
> insert into t
> select erg.* from (
> select d1.s from (select k,s from k1) as d1
> right join (select k,s from k2) as d2 on d1.k = d2.k
> ) as erg
> where s > 10
> I will attach the file "repro.sql", containing all SQL statements required to
> reproduce it (including the CREATE TABLEs).
> These are my investigation results:
> Conditions
> -------------
> 1. the outermost statement must NOT be a SELECT (e. g. INSERT)
> 2. there has to be a outer join in the subselect, where at least one dataset
> has no join partner
> 3. an outer SELECT must have a restriction (WHERE clause) and access a column
> from the table, that did not have a join partner
> Error state
> -------------
> The NullPointer occurs inside a generated class. So i enabled the Debug
> Option "DumpClassFile", to get the generated class file (the decompiled java
> class file will also be appended).
> The method "e2", stated in the StackTrace, performs the restrction "where s >
> 10". Therefore it calls getColumnFromRow() with its resultSetNumber.
> This is where the error occurs: there is no "current row" available.
> Precisely, the "row" property of the activation class at the specified index
> (which is the resultSetNumber=3 in this example) is not set.
> It gets a bit complicated now, I will try to explain it, starting with the
> generated resultset hierarchy.
> This tree of resultset implementations is generated to perform the query:
> Implementation resultSetNumber
> ------------------- ---------------------
> InsertResultSet -> none
> ProjectRestrictResultSet -> 5
> ProjectRestrictResultSet -> 4
> HashLeftOuterJoinResultSet -> 0
> TableScanResultSet -> 1
> HashTableResultSet -> 3
> TableScanResultSet -> 2
> The HashTableResultSet, which got the resultSetNumber 3 doesn't set a current
> row, because there is no join partner (still everything correct). But the
> ProjectRestrictResultSet on position 4 uses the restriction method ("e2"),
> which accesses a column on resultSetNumber 3 -> error.
> As far as I can tell, a restriction must never relate to the source of an
> outer join ResultSet. The numeration error does not occur, if the outermost
> statement is a SELECT and the numeration is generated top-down.
> Unfortunately I couldn't find an easy solution for this problem. In my case,
> this is a critical bug, because changing the query as workaround is
> difficult, since parts of it are generated. Please note, that this error is
> not dependent on any environment settings or platform and occured with all of
> the abolve mentioned versions. I didn't test the versions from 10.6 to 10.7,
> but probably those are also affected.
> If you require any further information, please let me know. I'm able to
> perform a build, so I wouldn't need a full version, a patch would be
> sufficient.
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