dovecot - Jul 2011 - Dovecot indexes

Hi,

could someone answer my following questions about dovecot indexes?

- If I delete dovecot indexes, it recreates them without any problem, right?
- If dovecot recreates indexes, it does not affect users (they don't
have to download all emails again, seen flag is not lost etc.) or is
there any problem?
- If I use mail_location = ...:INDEX=MEMORY, it recreates indexes
every time dovecot is (re)started, right? Does it have any negative
effect except performance/resources?
- Is there any difference in indexes for mbox and maildir (related to
previous questions)?

Thanks
Mike

On 07/08/2011 04:35 AM, Mike Prispan wrote:
> Hi,
>
> could someone answer my following questions about dovecot indexes?
>
> - If I delete dovecot indexes, it recreates them without any problem,
right?
I believe this depends.  Maildir and mbox I don't think care.  However, 
dbox and mdbox do and you'll lose information.  (from memory, I could be 
off)

On 08/07/2011 11:35, Mike Prispan wrote:
> could someone answer my following questions about dovecot indexes?
>
> - If I delete dovecot indexes, it recreates them without any problem, 
> right?
AFAIK,

for mbox and Maildir: True,

for sdbox and mdbox: False.
> - If dovecot recreates indexes, it does not affect users (they don't 
> have to download all emails again, seen flag is not lost etc.) or is 
> there any problem?
AFAIK this is true, at least for the cases where indexes can reasonably 
be recreated (mbox and Maildir).

AFAIK,
under mbox, Dovecot stores UID and flags in the message headers;
under Maildir, Dovecot stores UID in dovecot-uidlist file, and flags in 
filename.

AFAIK, under sdbox and mdbox, UID and flags are stored (only) in 
"indexes". sdbox and mdbox "indexes" cannot be recreated. If
sdbox or
mdbox "indexes" are lost, Dovecot will re-create them, but losing data
to a greater or lesser extent.
> - If I use mail_location = ...:INDEX=MEMORY, it recreates indexes 
> every time dovecot is (re)started, right? Does it have any negative 
> effect except performance/resources?
AFAIK, INDEX=MEMORY causes Dovecot to recreate indexes every time a 
mailbox is opened, not just when Dovecot is restarted.

Not aware of any negative effects other than the categories mentioned, 
but I can't claim to be an expert.
> - Is there any difference in indexes for mbox and maildir (related to 
> previous questions)? 
See http://wiki2.dovecot.org/IndexFiles

Bill