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From Dan Denton <>
Subject Tomcat/JDBC Thin Client and Oracle SQL Parsing
Date Tue, 26 Jan 2010 17:40:32 GMT
Hello all. Several days ago we saw some strange behavior with an Oracle database after the
restart of a tomcat webapp. Immediately after restart, Oracle was processing the query for
a certain page using an improper index that caused the page/query to hang. We've taken a look
at the configuration for our CBO and come to the conclusion that Oracle should not have reparsed
the query unless the query were somehow different, but we can't find anything to indicate
the query changed.

While it's possible there's something we missed, I would like to know if anyone out there
knows why a webapp restart would cause the database to reparse and choose a new execution
plan. We're running Tomcat 5.5.12 with JDK 1.5.0_12. This is on an RHEL4 server running a
2.6.9 kernel. The tomcat instance is using a JDBC thin client to connect to the database.
I know of no queries that are made to the database immediately upon startup, and it's certainly
not this one since the query is page specific.

Can anyone point out any instances they've had where Tomcat or Tomcat with the Oracle JDBC
driver has exhibited similar behavior?

Many thanks in advance,


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