Dovecot and FTS experiment

[Aki Tuomi]

> On 29 January 2019 at 19:15 Tomasz Nowak <tomek at flup.pl> wrote:
> 
> 
> Hello,
> 
> I'm trying to experiment with Dovecot and Solr server.
> I have >30k email addresses that I want to index to speed up searching 
> and save IOPS on mail servers.
> For now - I'm doing some experiments and I'm testing how it is working. 
> I'm thinking about adding one additional server with Solr and
> configure all mail servers to use that server.
> 
> I have some questions.
> 1. I have 15 mail servers. It will be good If I add new server with Solr 
> and use it on all Dovecot servers? Or maybe I should install Solr on all 
> mail servers?

Possibly, it's hard to say. It depends more about how much mail you have in total. You might need more than one server. One per backend is definetly too much.

> 2. I notice - I have mail account with 3GB of mail. Index files in mail 
> dir has 5MB. After indexing mailbox in Solr - index files has 15MB. What 
> changes in those files? FTS indexing adds something to that files - but 
> what?

You can use doveadm dump /path/to/index/directory to view the contents on the indexes.

> 3. If I need to disconnect Dovecot from Solr server - simply Can I 
> remove plugin configuration from dovecot.conf and everything would be 
> working? Or maybe - I need to remove index files and recreate it? It is 
> important for me because if some day I would decide to disconnect FTS 
> server - I would have to recreate indexes for >30k mailboxes..

You can just stop loading fts.

> 4. What if some day I want to change Solr server to new server with 
> empty Solr database? I can simply reindex mailboxes? Or I need to do 
> something more?
> 

You can run doveadm fts rescan -A and doveadm index -A "*" to perform full FTS indexing.

> Thanks!

Aki