Hi Lon, so with a context-local cache, you would still execute a regular query, but that query would not actually hit the database but the cache would return the result instead? Is it like a result set per query SQL string which is cached? I don't really understand how those local caches are keyed.
If there is any Cayenne documentation explaining this which I missed, I'd be happt to get a pointer to that. Maik > Am 24.02.2017 um 18:25 schrieb Lon Varscsak <lon.varsc...@gmail.com>: > > I built something similar in EOF to local cache, so I think I can answer at > least part of the question. > > It’s not uncommon for me to have a complex set of queries to do something > like compute pricing on an order. Rather than having to maintain many tiny > caches or ivars with query results, all of my code executes queries to get > the data set it needs whenever the pricing calculation is called. It makes > the code simpler, but gives you the performance of having stored the > results yourself in an ivar (or dictionary). > > Add in EHCache and now you can control how long those objects live (rather > than the life of an ivar). If they get removed from cache due to cache > control settings, the next time through the code, it will refetch them but > I don’t have to be aware of this from a code perspective. > > Where I’m still hung up, is that it’s common for me to have many parts of > my code that are not aware of each other that display/operate on the same > data, and I’m unsure how to update the cache (since there are multiple > local caches) in between those two components after commit (since change > propagation is turned off by default and even when on is in a separate > thread so I can’t assume the objects will be refreshed when I need). > > -Lon > > On Fri, Feb 24, 2017 at 3:00 AM, Musall, Maik <m...@selbstdenker.ag> wrote: > >> Hi all, >> >> I'd like to extend this question a bit. I just read the entire performance >> tuning chapter again [1], and I'm a bit puzzled especially about the >> ObjectContext's local caches, which Andrus also recommended to use in the >> "A way to refreshObject()" thread: >> >>> So instead of micro-optimizations with shared snapshot cache, you should >> use queries with cache groups and query cache. They get refetched when a >> cache group is flushed in response to an object commit. So technically you >> are not reusing the snapshot cache, but it really doesn't matter. The >> benefit you get in code simplicity, consistency, and often performance, >> always outweighs that. Besides this approach is cluster-friendly. >> >> Coming from EOF I grew the habit of frequently creating short-lived >> ObjectContexts, so basically every page load uses it's own new >> ObjectContext to get fresh data from the shared global cache, because other >> users may have altered data between page loads. While working on a page, I >> have references to the objects that I need there anyway, so I don't >> understand at all what that context-local cache mechanism should do for me, >> unless that "create new contexts all the time" strategy is just plain wrong >> for Cayenne-based applications? >> >> And even if I would use a longer-lived ObjectContext for something, where >> would that local cache get in effect? Either I have references to objects >> anyway, or I would need to refetch them, which would go through to the >> database, right? In what case would I get a benefit from a local cache? I >> didn't find answers to this in the Cayenne Guide. >> >> Thanks >> Maik >> >> [1] https://cayenne.apache.org/docs/4.0/cayenne-guide/ >> performance-tuning.html <https://cayenne.apache.org/ >> docs/4.0/cayenne-guide/performance-tuning.html> >> >> >>> Am 23.02.2017 um 09:43 schrieb Markus Reich <markus.re...@markusreich.at >>> : >>> >>> Hi, >>> >>> I'm looking for a more detailed explaination of the caching mechanism, as >>> we are running a quite important and big web application with cayenne, I >>> want to fine tune, because we run in some performance issues. >>> >>> I only found this >>> https://cayenne.apache.org/docs/3.0/individual-object-caching.html >>> >>> In 4.0 docu I can't find anything >>> >>> br >>> Meex >> >>
