Hello Vikas, On 18/08/2014 12:05, Vikas Saurabh wrote: > Hi, > > ... > specify a cache size. While I agree that cache should be a memory > hog... but entry size of a document in cache is quite variable in > nature and as an admin I can make guesses about JCR nodes and their > access patters. Document size, otoh, would vary even during the > lifetime of repository. > > Moreover, the only downside (assuming RAM is cheap) of increasing > cache to large number is making cache invalidation expensize. > > So, IMHO, document caches should be limited in terms of number of > entries in cache. And if we still want to have byte size limitation, > we can probably have both and cache respects whichever constraint hits > first (sort of min(byte size, entry size)). First of all I don't know MongoNS implementation details so I can be wrong.
I'd rather keep the size in bytes as it gives me much more control over the memory I have and what I decide to provide to the application. If we say, to take an extreme example, 1 document only in cache and then this single document exceed the amount of available memory I fear an OOM. On the other hand having bytes ensure us the application keeps working and it will be task of a sysadmin to monitor the eventual hit/miss ratio to adjust the cache accordingly. About cache invalidation I'm not sure but it could be that the MongoNS implementation uses off-heap for caching. Cheers Davide
