Re: Re: Receiving the all the entries that belongs to a group

I am using a database Chris,
but because the client (which is a stand alone application) requires huge amouns of data, is completly ineficient to get from database the query results at each request. In my opinion caching the result of a db query, is a classical use case for using a cache library . Unfortunalty, the current persisten listener of oscache, is very slow when is storing large amount of data.

----- Original Message -----
From: Chris Miller <[email protected]>
Date: Wed, 24 Dec 2003 17:46:54 +0000
To: [email protected]
Subject: [Opensymphony-oscache] Re: Receiving the all the entries that      belongs to a group

> You're using the wrong tool to solve your problem. You really should be 
> using a database for this, it's exactly the type of problem they're 
> designed to handle after all!
> 
> 
> Romulus Pasca wrote:
> > I have in my application a huge cache which cannot be keep it in
> > memory(arround 200MB). So I intended to use a cache with a small
> > memory size, and unlimited disk size. Also my entries should never
> > expire(are read-only persistent objects). I wanted to keep different
> > type of entries(I have around 25-50 types of objects that should be
> > cached) in different groups. The keys for entry are a specific prefix
> > for each group appended to the hash code of the object (which is
> > guaranted to be unique). For some types of entries, for which I load
> > all the required data at startup(other entries can be added also
> > during the application life time, but these entries are never
> > deleted) I have a business requirement, which asks me for all the
> > entries of that type. So it looks like I need to get all entries for
> > a group(both from memory and disk)- a statical snapshot with the
> > members of the group at a specific time. 
> > 
> > Assuming that it's ok for me to get a statical snapshot of a group, I
> > added to the Cache class the following methods:
> > 
> > public Object[] getGroupFromCache(String groupName, Class entryType) {
> >         Set groupEntries = cacheMap.getGroup(groupName);
> >         ArrayList result = new ArrayList();
> >         if (groupEntries != null) {            
> >             Iterator itr = groupEntries.iterator();            
> >             while (itr.hasNext()) {
> >                 try {
> >     result.add(getFromCache((String) itr.next()));                    
> >                 } catch (NeedsRefreshException ne) {
> >                     //just ignore this entry
> >                 }
> >             }
> >         }
> > return result.toArray((Object[])
> > java.lang.reflect.Array.newInstance(entryType, result.size()));
> >     }
> > 
> >     public Object[] getGroupFromCache(String groupName) {
> >         return getGroupFromCache(groupName, Object.class);
> >     }
> > Is in your opinion, Chris this code ok? 
> > 
> > Regarding the performance of the OSCache(because I follow the
> > performence discussion about oscache form this mailing list), I have
> > big performance problems with my caching model. As I told you I need
> > a huge disk-based cache for my application. At my first test with
> > OSCache, I was tring to store each item of a big search in the
> > cache(there was thousands of items, with a total size of 35MB).
> > Without OSCache, the time for this serach was just around a minute.
> > When I was trying to store these entries with OSCache, the time jump
> > to more then 2 hours.  So it looks that the default persistent
> > listener is not suitable for such kind of scenarios...
> > 
> > Best Regards and Merrie Christmas!
> > Romulus
> 
> 
> 
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