[horde] IMP IMAP DB Cache backend lifetime

[Joao S Veiga]

----- Message from Jens Wahnes <wahnes at uni-koeln.de> ---------
> Federico Giannici wrote:
>
>> As you can see, the number of cached folders is decreased al lot  
>> (by 80%) but the number of cached messages decreased a lot less  
>> (only 30%).
>>
>> 4 MILLIONS records and 8.2 GB are simply too much for the DB to be  
>> adequately fast.
>
> I think you'd be better off putting cached IMAP data somewhere else,  
> e.g. into memcached. Except for a tiny Horde installation with very  
> few users, there's really no point in keeping that kind of data in a  
> relational database, and most likely it does not even make sense to  
> store that kind of cached data on disk.
>
> When you put that stuff into memcached instead, it will  
> automatically expire when your memcache gets full, which may not be  
> the totally by the book, but should work out ok in practice.
>

Hi Jens,

Even with very few users, without Frederico's suggestion the cache in  
the database will grow forever if not manually cleared (and the  
imp-query-imap-cache doesn't help much for old messages/metadata).

So for the sql cache to properly work in any case, there should be a  
way to expire them, as he suggested.

best regards,

Joao