You really aren't going to get a useful answer to this question without doing some testing yourself. There are several factors that can influence this:
- How many items are you putting into Memcache? - How large are the items? - Are you forcing the old items out via LRU? Other applications with even only minor deviations in numbers from yours will see significantly different results simply due to different usage patterns. I like the way you're approaching the problem - non-critical data that is regularly flushed. This is the way we'd like to encourage developers to think about how to scale their applications: differentiating between what is critical, non-critical, what can be done synchronously versus what can be done asynchronously. I'd toy with the cron jobs and track a miss rate as a function of the length of the cron job interval. There's probably a stable balance between acceptable miss rate and minimizing datastore updates you can achieve that may very well change with time as you change the data being saved or as your application's usage patterns shift. On Sun, Feb 7, 2010 at 4:34 AM, a.maza <[email protected]> wrote: > Hello, > > I am keeping non-critical data (which is updated quite often) in > memcache. I would like to use a cronjob to fetch the data in frequent > intervalls from memcache in order to persist it to the datastore. > > Thus, I would be interested if anyone has any experiences with the > average expiration time of entities that are kept in memcache (and > there quite frequentally accessed) - 5min? 10min? > > Thanks and regards, > andr > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to > [email protected]. > To unsubscribe from this group, send email to > [email protected]<google-appengine-java%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > > -- Ikai Lan Developer Programs Engineer, Google App Engine http://googleappengine.blogspot.com | http://twitter.com/app_engine -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
