On 9/4/12 4:11 PM, Alain Kuchta wrote:
Hi all,
I’m developing a program to move database from some other DBMS
database to a derby database. To accomplish this I’m making a java
application and implementing batch prepared statements. The batch is
very large (13000+ statements). When the program runs I receive this
exception:
Caused by: java.lang.NullPointerException
at
org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeBatchElement(Unknown
Source)
at org.apache.derby.impl.jdbc.EmbedStatement.executeBatch(Unknown Source)
at com.etegent.tools.SqlDataTransferTool.SqlDataMover.transferTable(
SqlDataMover.java:207 )
The PreparedStatement object used to execute the batch is not null.
Also, by querying the destination database after the program ran, I
noticed that all of the rows that I had desired to move, had been
moved. Doing some debugging I noticed that the Vector<E>
batchStatements which is a member of the PreparedStatements object,
had extra elements, A LOT of them. 13171 elements were populated and
7309 elements were null. I observed similar behavior with a smaller
set of batchesand I am pretty sure this is typical vector behavior.
However, I do not receive the above exception when using smaller
batches. Such as 10 statements. I suppose a work around for now is to
do smaller set of batches. Is this a known limitation of derby? Any
idea why this may be happening?
-Thanks
Alain Kuchta
Hi Alain,
A NullPointerException is definitely a Derby bug. If you can script this
problem and log a JIRA, we should be able to fix it.
Another approach to bulk-importing data is to wrap your access to the
other database in a ForeignTableVTI (see
https://issues.apache.org/jira/browse/DERBY-4962).
Hope this helps,
-Rick
