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Posted to derby-dev@db.apache.org by Rick Hillegas <ri...@oracle.com> on 2011/03/09 15:13:02 UTC
outstanding bugs in the automatic calculation of statistics
Here are the open bugs in this area which I know about. Are there others?
o DERBY-5045: The best theory about this problem is that there is a
pre-existing DataDictionary bug which fails to scour cruft out of
SYSSTATISTICS after a table is dropped. The consequence of this
pre-existing bug is that harmless junk tuples may slowly accumulate in
SYSSTATISTICS for applications which have not converted from using DROP
TABLE to using TRUNCATE TABLE. This does not appear to be a regression
or even a user-visible problem.
o DERBY-5097: This appears to be a timing-related problem in which
automatically calculated statistics are not computed soon enough. There
may be a real istat bug here or this may be a heisenbug in the test
itself. In any event, this does not appear to be a regression. The
consequence of this problem is that istat may not deliver its benefits
fast enough in some situations. This will not cause wrong results and
this will not cause queries to run any slower than they did in previous
releases.
Thanks,
-Rick