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https://issues.apache.org/jira/browse/DERBY-3230?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12557482#action_12557482
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Kathey Marsden commented on DERBY-3230:
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Thanks Bryan for your comments on this issue so far.
I am taking a look at this issue and have a question about the position logic
in the client. The failure occurs in this code because position_ =
lastValidBytePosition_ in the following code in NetCursor.
private int readFdocaOneByte() throws
org.apache.derby.client.am.DisconnectException, SqlException {
// For singleton select, the complete row always comes back, even if
multiple query blocks are required,
// so there is no need to drive a flowFetch (continue query) request
for singleton select.
if (position_ == lastValidBytePosition_) {
// Check for ENDQRYRM, throw SqlException if already received one.
checkAndThrowReceivedEndqryrm();
.......
There is no javadoc for lastValidBytePosition, nor currentRowPosition and
nextRowPosition which seem to be at play here as well. I haven't really been
able to figure it all out from the code yet.
I'd most appreciate an explanation of the interplay of the various positions
if someone understands it, so I can understand why position ==
lastValidBytePosition and why that is a bad thing in this case. I will add any
explanation as comments to the code.
Kathey
> Selecting data from a Table raises Error XN008: Query processing has been
> terminated due to an error on the server
> ------------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-3230
> URL: https://issues.apache.org/jira/browse/DERBY-3230
> Project: Derby
> Issue Type: Bug
> Components: Network Client, Network Server
> Affects Versions: 10.3.1.4
> Environment: Windows XP
> Reporter: Stefan Huber
> Priority: Critical
> Attachments: test.rar
>
>
> I got a table (PCLASS) in my database where I cannot select the data via a
> simple select statement:
> - If I execute 'select * from PCLASS': XN008: Query processing has been
> terminated due to an error on the server
> - If I execute 'select * from PCLASS order by CLASSNAME': it works
> - If I add or remove only one row to/from the table: it works
> If I use the embedded driver everything works fine. But as soon as I use the
> derby network client to access the database, this problem occurs.
> This is very odd. I spent a lot of time to do some research on this behavior
> because I could not believe that the network client produces errors depending
> on the data contained in a table. But after all it looks like I managed to
> fill the table with an exact amount of data that causes this error to arise.
> To reproduce the problem download the attached file and follow these
> instructions:
> * extract test.rar to $derby.system.home$
> * start derby network server
> * start ji utility and execute the following commands:
> ** connect to database test using client driver:
> connect 'jdbc:derby://localhost/test;user=ZOL;password=zol';
> ** select content of table PCLASS
> select * from PCLASS;
> --> Error XN008: Query processing has been terminated due to an error on the
> server
> ** disconnect from database
> disconnect;
> ** shutdown database 'test'
> connect
> 'jdbc:derby://localhost/test;user=ZOL;password=zol;shutdown=true';
> ** connect to database 'test' using embedded driver:
> connect 'jdbc:derby:test;user=ZOL;password=zol';
> ** select content of table PCLASS
> select * from PCLASS;
> --> everything o.k.
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