[Dovecot] Question about pre-indexing maildirs

[Timo Sirainen]

On 21.6.2007, at 3.50, David Favor wrote:

> I have a situation with many users and an existing mail delivery
> agent. Seems like I once saw an imaptest program which I imagine
> might be used to pre-index maildirs.

imaptest is mostly useful for benchmarking and stress testing.  
Although stress testing your server with your users' mailboxes does  
index the maildirs, it's not really the optimal solution. :)

> For example...
>
>    - remember which users and user maildirs have changed since
>      last pre-index
>
>    - when system quiet pre-index any maildirs which have had
>      mail delivered and no access by a mail client (using some
>      inotify magic)

The main problem I see with this is that "indexing" isn't that  
simple. http://wiki.dovecot.org/IndexFiles has some explanations how  
it works.

The most useful thing a pre-indexing can do is to update cache file,  
but different clients use different fields, so your pre-indexing  
should cache all those fields, and preferrably not more because that  
will then cause extra disk I/O for the cache file.

I don't think there's any easy way to make Dovecot cache the useful  
fields. Or perhaps fetching RFC822.SIZE for all messages causes that,  
at least it should for v1.1 but I'm not sure about v1.0. You could  
try and then check if all the fields were added to cache file. You  
can check that with:

idxview dovecot.index dovecot.index.cache

I should probably build some indexer binary that updates the index/ 
cache files with all the useful changes.
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