Dear MonetDB Team,
We're starting to exercise our MonetDB installation more heavily now and I've run into a strange issue where I get an occasional "COMMIT: failed" message.
It seems that the conditions required to produce this are:
- Concurrently inserting into two different tables - At the same time, issuing a SELECT COUNT(*) against either of those tables
I've logged a bug with more detailed information, including a Java test case:
http://bugs.monetdb.org/show_bug.cgi?id=3210
I'm only just starting my investigation, but I suspect that COUNT(*) may be the culprit, since other selects like SELECT * don't seem to have this problem.
Does this ring any bells? Are there any special optimizations for COUNT(*) that bypass the underlying BAT and/or have side effects on some shared table somewhere that could be causing a concurrency violation?
Thanks,