expunging messages doesn't update maildirsize

[WJCarpenter]

On 04/19/2016 07:17 PM, WJCarpenter wrote:
> Is it by design that dovecot doesn't update maildirsize immediately 
> when messages are expunged? If yes, why?

Replying to my own question since I figured it out. Local config glitch, 
not a dovecot bug or design fault.

I should have mentioned that I don't use dovecot's local delivery agent. 
Updates to maildirsize for newly arriving messages is done by exim.

Boring details follow. They become interesting details if you are having 
the same problem. :-)

I use the SQL backend for keeping track of user data, including quota 
values. Consequently, I have configured 3 very similar (but not 
identical) SQL queries for that user data. One is in my exim config, and 
two (password_query and user_query) are in my dovecot-sql.conf.

Those of you familiar with dovecot's SQL queries will know that the 
password_query can also return values that would ordinarily be looked up 
via user_query, the motivation being that user_query can often be 
skipped completely. The dovecot 2.2.9 release broke that userdb prefetch 
feature (it was fixed soon after, but I am using my distribution's 
dovecot version [Ubuntu 14.04], which is stuck at 2.2.9). Even though 
userdb prefetch doesn't work and both passdb and userdb queries are both 
done every time, my user_query is just a clone of my password_query in 
anticipation of the day when I can get rid of user_query.

It's the cloning of the query where things went wrong. In the 
password_query, the prefetched user quota value is returned as 
"userdb_quota". In the user_query, it's returned as "quota". When I 
cloned the query, I neglected to change "userdb_quota" to "quota" in my 
select list. (That's a bummer, because I did correctly change 
"userdb_home" to "home" in my select list, so I must've known I should 
do it.)

The net is that dovecot did the password_query and got the correct value 
for the user quota. It then ignored that (due to the prefetch bug) and 
did the user_query. The user_query reported the user quota with the 
wrong field name, and dovecot figured there was no quota for that user 
(which means /every/ user).

Once I fixed my 7-character configuration mistake, it started working 
correctly.

For the sake of brevity, I've left out the parts where I went down a 
bunch of blind alleys before finding the correct solution. :-)