I'm not sure why this is happening, but I've been getting what seems
randomly appearing nulls when I call next() with every 3.0.x driver
version to date. It does not happen with the 2.0.x driver.

I'm currently running mysql 4.0.12, but it has occurred on prior 4.0.x
versions.

My process is reading through a large result set (100,000+ rows), and I
am updating data on another connection. I'm not sure what detail I can
give here, as, the error seems random.

Exception in thread "main" java.sql.SQLException:
Error trying to fetch row:null
at
com.mysql.jdbc.RowDataDynamic.nextRecord(RowDataDynamic.java :280)
at com.mysql.jdbc.RowDataDynamic.next(RowDataDynamic.java:244)
at com.mysql.jdbc.ResultSet.next(ResultSet.java:2418)
<rest of my stack dump>

Has anyone else had this happen? I have never got this exception on the
2.0 driver, but seems to randomly happen on the 3.0.x driver.

If more information is needed, reply to my email address, and I can dig
further.

Thanks.


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Mark Brown writes:
> I'm not sure why this is happening, but I've been getting what seems
> randomly appearing nulls when I call next() with every 3.0.x driver
> version to date. It does not happen with the 2.0.x driver.
>
> I'm currently running mysql 4.0.12, but it has occurred on prior 4.0.x
> versions.
>
> My process is reading through a large result set (100,000+ rows), and I
> am updating data on another connection. I'm not sure what detail I can
> give here, as, the error seems random.
>
> Exception in thread "main" java.sql.SQLException:
> Error trying to fetch row:null
> at
> com.mysql.jdbc.RowDataDynamic.nextRecord(RowDataDynamic.java :280)
> at com.mysql.jdbc.RowDataDynamic.next(RowDataDynamic.java:244)
> at com.mysql.jdbc.ResultSet.next(ResultSet.java:2418)
> <rest of my stack dump>
>
> Has anyone else had this happen? I have never got this exception on the
> 2.0 driver, but seems to randomly happen on the 3.0.x driver.
>
> If more information is needed, reply to my email address, and I can dig
> further.
>
> Thanks.
>

This looks like a possible bug, but we truly need a repeatable test
case.

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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Sinisa Milivojevic wrote:
> Mark Brown writes:
>
>>I'm not sure why this is happening, but I've been getting what seems
>>randomly appearing nulls when I call next() with every 3.0.x driver
>>version to date. It does not happen with the 2.0.x driver.
>>
>>I'm currently running mysql 4.0.12, but it has occurred on prior 4.0.x
>>versions.
>>
>>My process is reading through a large result set (100,000+ rows), and I
>>am updating data on another connection. I'm not sure what detail I can
>>give here, as, the error seems random.
>>
>>Exception in thread "main" java.sql.SQLException:
>>Error trying to fetch row:null
>> at
>>com.mysql.jdbc.RowDataDynamic.nextRecord(RowDataDynamic.ja va:280)
>> at com.mysql.jdbc.RowDataDynamic.next(RowDataDynamic.java:244)
>> at com.mysql.jdbc.ResultSet.next(ResultSet.java:2418)
>><rest of my stack dump>
>>
>>Has anyone else had this happen? I have never got this exception on the
>> 2.0 driver, but seems to randomly happen on the 3.0.x driver.
>>
>>If more information is needed, reply to my email address, and I can dig
>>further.
>>
>>Thanks.
>>

Connector/J 2.0.14 didn't have the ability to 'stream' result sets like
3.0 has, and it appears you've changed something in your code to start
using 'streaming' result sets for this particular query (otherwise the
driver would be using RowDataStatic, which is the default).

If the connection that is reading streaming rows is closed by the server
(due to your code taking too long (> than 'net_write_timeout' between
requesting rows, for example), you could get an exception,. Ideally, if
you could run your code in a debugger, and set a breakpoint on line 280
of RowDataDynamic, you could see what the underlying exception is.

Is there a reason you can't use the old form of result sets in this
case? (i.e, the default behavior)?

-Mark


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__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Mark Matthews <mark [at] mysql.com>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, SW Dev. Manager - J2EE/Windows
/_/ /_/\_, /___/\___\_\___/ Flossmoor (Chicago), IL USA
<___/ www.mysql.com
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