]
Steven Hawkins commented on TEIID-1648:
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Removed the KI from the release notes as we have the translator copyLobs property and the
threadbound property TEIID-2619 that can force lobs to read by the calling thread prior to
be used in another thread. A further refinement would be targeted at just performing the
copyLobs/type correction in the translator thread rather than making the execution
threadbound - which will the performance/amount of data pulled/saved for all queries not
just those with lobs.
Reading CLOB's from Teradata has issues and produces exception
when stream is read from a different thread than what the clob was read from the
resultset
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Key: TEIID-1648
URL:
https://issues.jboss.org/browse/TEIID-1648
Project: Teiid
Issue Type: Bug
Components: Misc. Connectors
Affects Versions: 7.4.1
Reporter: Van Halbert
Assignee: Steven Hawkins
Priority: Critical
Attachments: JDBCQueryServlet.java
The initial problem was seen when running BQT testing against the teradata source.
However, when debugging, the exception was occurring on the initial client read of the
stream. After reading teradata jdbc driver doc, it talks about how its not thread safe
and has issues when different threads are handling blobs/clobs. Which lead me to do a
simple client test. 2 tests where run run thru a servlet that obtains the teradata
connenction via jndi. Thet are as follows (attached is the sample code after the changes
used for #2):
1. simple execute/select: execute select intkey, objectvalue from bqt1.smalla, for
each row, obtain the clob and read the stream (no exception is seen)
2. execute select and read clob in a different thread: a new thread is created,
passing in the clob, thread is started and then proceeds to try to read the stream,
exceptions are seen
I'll attach the sample code.
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