[dovecot] Re: index files

[Farkas Levente]

Timo Sirainen wrote:
> On Wed, 2003-04-23 at 11:26, Farkas Levente wrote:
> 
>>ok the whole story:
>>- once (one of the cvs version) we got a few corrupted index file.
>>- then I delete all index file
>>- after that (as I wrote it) the load goes so high I've to stop dovecot.
>>- delete all index file and modify dovecot.conf :
>>   mail_cache_fields =
>>- but now I assume the index and high load problem may be solved so I'd
>>   like to put back the default cache schema.
> 
> 
> But currently there's no real high load problems with empty
> mail_cache_fields?

no currently ther is not. that's why I'd like to test what happens if I 
trun it back.

>>and my question is:
>>should I delete the old index files (which contains no fileds) in
>>order to create new index files (which contains the default fields) or
>>it will happned automaticaly?
>>from you first answer it seems to me if the index is not corrupted than 
>>it never will recreated. but from the second it seems it will regenerate 
>>it automatically?
>>so?
> 
> 
> It goes like this:
> 
> - When index is first created, mail_cache_fields setting is saved into
> header.cache_fields. All existing mails are indexed with those fields
> cached
> - If client does something where a cached field would have been a
> speedup, but the field isn't cached, header.cache_fields is updated to
> include that field
> - All new mails that are indexed will have the new field cached as well,
> but the old ones aren't changed
> - If client again does it with an old mail where it wasn't indexed, then
> Dovecot will rebuild the cache for all mails in the index so they all
> contain the wanted cached fields
> 
> So even if you don't cache anything initially, they should get
> automatically cached if client wants them. Clients behave very
> differently so we don't automatically cache everything, if cached field
> is not needed it just slows down things.
> 
> This still isn't the optimal caching behaviour, some clients cache
> everything locally and fetch data for only new mails. In that case
> cached fields would be mostly useless. Even if that client or some other
> occationally fetches some data again, it's likely better for overall
> performance if nothing is cached.

ok. so I don't have to delete them and force the regeneration.


-- 
   Levente                               "Si vis pacem para bellum!"