> SELECT thingIdx, thingName FROM Things WHERE thingIdx IN (?, ?, ?, ?, 
> ... [100 values scattered throughout index])
> 
> performance is pretty slow -- a bit over a minute for 100 records. 

I believe this is DERBY-47 (http://issues.apache.org/jira/browse/DERBY-47),
also logged as DERBY-713 (http://issues.apache.org/jira/browse/DERBY-713).

There are a number of suggestions in those two bug reports for ways to
work around the problem.

I don't believe there is a fix yet, so for the time being it is advisable
to avoid the problem.

thanks,

bryan