Set the time for as long as you can acceptably use cached data. (days if you can)
Just dont expect it to be there all the time, AppEngine can and will evict the cache as it needs the memory. Actual retention is based more on usage of the data rather sticking to the expiration time. So data that gets used more will hang around longer (upto its expiration time) than rarely used data. (on the basis that data that is getting read lots is actully the most useful - its saved more hits on the origin datasource) On 26 February 2010 13:51, xcdesz <[email protected]> wrote: > Thanks -- that is useful to know. Do you know if there is a maximum > expiration time -- for example, if I set expiration to something like > 4-8 hours, would that be a bad practice? > > On Feb 26, 4:29 am, Barry Hunter <[email protected]> wrote: >> According to the Documentantion the JCache implementation is just a >> wrapper around memcache >> >> http://code.google.com/appengine/docs/java/memcache/ >> >> With memcache you explicitly set the expiration time you want on how >> long the data should survive for. >> >> The 'memory' is actually distributed and lives outside the JVM, so is >> shared by all instances (if you have multiple running), and does >> survive JVM restarts. >> >> On 25 February 2010 20:49, xcdesz <[email protected]> wrote: >> >> > I am confused about how JCache works with Google's cloud, and have >> > some basic questions that I havent been able to find answers for.. >> >> > Suppose I am using JCache to store query results (i.e; a list of blog >> > postings), so that users do not have to hit the datastore when >> > initially logging on to a site. If I have a low-traffic situation, >> > where one user logs in and logs out after a few minutes, and another >> > user might not log on for another hour or so -- do those query results >> > stay in JCache long enough for the other user to see the cached >> > results of the previous user? >> >> > I'm trying to reduce the "loading request" time by using cached >> > results instead of the datastore. Is this possible, or does the >> > JCache instance (and JVM, for that matter) die pretty quickly after >> > inactivity. Does JCache live and die with the JVM -- or is it >> > somewhere else? >> >> > -- >> > You received this message because you are subscribed to the Google Groups >> > "Google App Engine" 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 >> > athttp://groups.google.com/group/google-appengine?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" 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?hl=en. > -- You received this message because you are subscribed to the Google Groups "Google App Engine" 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?hl=en.
