Hello,
I plan to enable automatic calculation of index cardinality statistics
by committing DERBY-4938 and DERBY-4939 (I have broken up the code from
the latest DERBY-4771 patch, the patches are just not accessable for me
right now).
Before I do that, I want to ask is people think the regression tests are
stable enough. Enabling the auto-calculation may cause intermittent
failures, since the work is carried out in a background thread. Tests
that may experience failures are tests asserting on statistics and
locks, and which also perform SQL queries using indexes ([1]). If you
suspect the feature has caused an error, the first thing to do is to
grep for "istat" in derby.log.
It would be helpful wrt debugging if there aren't many intermittent
failures popping up already.
I can hold off for a while longer, but I want the feature to be tested
of many different types of operating systems and hardware before 10.8.
Opinions?
Regards,
--
Kristian
[1] The row estimates have to be recently up to date as well. How this
happens exactly is a bit fuzzy, but it often involves a table scan, and
may depend on things like checkpoints and table size.
