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From dag.wan...@oracle.com (Dag H. Wanvik)
Subject Re: Table exists in same JVM after Derby is shutdown
Date Fri, 05 Aug 2011 21:50:40 GMT
Pavel Bortnovskiy <PBortnovskiy@Jefferies.com> writes:

> Hello, all:
> While executing a bunch of JUnit tests within the same JVM (all executed 
> by IntelliJ IDEA) I started seeing strange and unexpected errors occurring
> .
> Upon closer inspection, I noticed that in many of those tests tables with 
> the same names are attempted to be created.
> Then I realized that although Derby is shutdown and then re-created, the 
> tables remain, thus causing collisions.

The "create=true" connection attribute is ignored (with a warning) if
the database with the same name alrady exists.

> I've created a digest (attached) which is executed as one JUnit test to 
> illustrate what I'm seeing.
> The behavior I would expect is that once Derby is shutdown, no tables 
> would remain in the JVM, and if a database (with the same name) is 
> re-created, it would be a tabula rasa.

The tables are no longer in memory (or should not be unless you found a
bug), but they are not erased from the disk image of the database.  As
per the above, one would need to explicitly delete it using OS file
system tools for the data to be cleared. Some JUnit tests delete tables
in TestCase#tearDown, others use singleUseDatabaseDecorator to isolate
itself from the rest of the tests. The tests not necessarily very
consistent in their patterns for this..


> Can you please let me know whether my expectations are erroneous and 
> whether I should find workarounds (albeit trivial to implement).
> However, what would concern me in that case is that the tables and the 
> data remain in the JVM, thus consuming memory
> (and, if unused, creating memory leaks).
> Thank you,
> Pavel.
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