How does the "merge metrics" work?

[Mahy]

Hello,

I built my own vulcan-metrics with 2 additional XSL transformations
and added it to the running Vulcan copy. The log showed that the
transformations do get recognized and run, but produce no results. But
it also showed that metrics merging is done before transformation. So
I altered the two XSL files to match template at "/", because I don't
know how the merged metrics file might look like. I it a simple
concatenation with added root element?

I'm sure my XSL files work, since I ran them many times even from Ant
in a build script to produce custom metrics for Vulcan. But when added
directly to the vulcan-metrics plugin, they produce no metrics.

Anyway, on the second attempt, it DID NOT show that my added
transformations (named jmeter.xsl and funkload.xsl) produced no
metrics, but instead this appeared in the vulcan.log:

2011/01/07 14:20:58 ERROR
net.sourceforge.vulcan.core.support.BuildManagerImpl: An error
occurred saving a build outcome for project Zabinec. The detailed
error message is "PreparedStatementCallback; SQL [insert into metrics
(build_id, message_key, metric_type, data) values (?, ?, ?, ?)];
integrity constraint violation: unique constraint or index violation;
UNIQ_KEY_PER_BUILD table: METRICS; nested exception is
java.sql.SQLException: integrity constraint violation: unique
constraint or index violation; UNIQ_KEY_PER_BUILD table: METRICS."
net.sourceforge.vulcan.exception.StoreException:
PreparedStatementCallback; SQL [insert into metrics (build_id,
message_key, metric_type, data) values (?, ?, ?, ?)]; integrity
constraint violation: unique constraint or index violation;
UNIQ_KEY_PER_BUILD table: METRICS; nested exception is
java.sql.SQLException: integrity constraint violation: unique
constraint or index violation; UNIQ_KEY_PER_BUILD table: METRICS


And the build did not save correctly. What's that supposed to mean? I
can upload the two XSL transformations for you to review (and possibly
add to main tree) if it helps. Just please explain what can be wrong
and how can I diagnose the problem. TIA