I think this is the right path, though would need more details: o does boot mean first time boot for each db? o how to determine "this machine" o and the total time to run such a test.
There are some very quick and useful tests that would be fine to add to the default system and do one time per database Measureing how long to do a commit and how long to do a single database read from disk would be fine. Seems like just these 2 numbers could be used to come up with a very good default estimate of log recovery time per log record. Then as you propose the actual estimate can be improved by meauring real recovery time in the future. I am not convinced of the need for the bigger test, but if the default is not to run it automatically and it is your "itch" to have such a configuration option then I would not oppose. I do see great value in coming up with a very good default estimate of recovery time estimate based on outstanding number of log records. And I even envision a framework in the future where derby would schedule other non-essential background tasks that have been discussed in the On a different track I am still unclear on the checkpoint dirty page lru list. Rather than talk about implementation details, I would like to understand the problem you are trying to solve. For instance I well understand the goal to configure checkpoints such that they map to user understandable concept of the tradeoff of current runtime performance vs. how long am I willing to wait the next time I boot the database after a crash. What is the other problem you are looking at. Raymond Raymond wrote: > Mike, > Last time we discussed about how to map the recovery time into Xmb of log. > I have been thinking on it recently and have a proposal. > How about when the very first time derby boots (not every time) on a > certain > machine, we let the user to chose whether he (or she) want to do some > statistic > collection about the system performance. If he (or she) want to do, > derby runs > some test, if not, derby doesn't run test. Later, just as what you said, > we let derby > collect information every time it does recovery to refine the former > information. > Thanks. > > > Raymond > > _________________________________________________________________ > Don’t just search. Find. Check out the new MSN Search! > http://search.msn.click-url.com/go/onm00200636ave/direct/01/ > >
