fts_solr: Error: fts_solr: received invalid uid '0'

[Daniel Miller]

On 9/13/2019 1:21 AM, Fabian via dovecot wrote:
> Hi,
> 
> we are trying to add full text search functionality with Solr to our Doveoct setup. Our Versions:
> OS: Debian 9
> Tried versions:
> - Dovecot 2.2.7 with Solr 3.6
> - Dovecot 2.3.4 with Solr 8.2
> (2.2.7 from offical Debian repository, 2.3.4 from backports)
> 
> Search is working mostly of the time perfrectly smooth. But sometimes following message appears in mail.err:
> dovecot: imap(username)<16189><UxYWLVuSYMasEQoK>: Error: fts_solr: received invalid uid '0'
> 
> If this error occurs our webmail frontend delivers most of the time a timeout. Sometimes the search only takes really long.
> 
> Are  there any ideas why this error occurs? We are not able to reproduce the error in such a way that it would always be reproducible. However, we can reproduce the behavior in some form over and over again - but we do not know exactly what is decisive.
> 

Are you limiting Solr's memory usage? How much available memory is on 
your server?

To shortcut the conversation - if you don't have at least 16G of *free* 
RAM it's time to upgrade. My own server has 32G installed - I used to 
have 16G. My own Solr problems basically disappeared after adding RAM. 
And I only serve a few users - my own mailstore is the largest as I keep 
most of my mails. If you're serving 20+ users you'd probably benefit 
from doubling to at least 64G.

--
Daniel