[syslog-ng] MongoDB destination driver

[Gergely Nagy]

> I agree with Matthew, that it would be really important to make this 
> driver "dynamic", as it would be a great tool combined with patterndb 
> for reporting without the need to pre-define fields and a dozen of 
> destination statements.

Aha! Apologies for being confused before: I have to admit, I never used
patterndb before, and totally forgot about it.

> It is actually not that hard to achieve (again, syslog-ng is a breeze), 
> pdbtool does quite the same when emitting all variables, the 
> nv_table_foreach() function is there to iterate over all of the 
> name-value pairs.
> 
> However the NVTable struct stores the builtin and dynamic values 
> separately and with a small copy-paste coding in nvtable.c you can grab 
> only the dynamic values.
> 
> Please find a patch attached that introduces the flags() option for the 
> mongodb driver and the auto_nvpairs flag, that inserts all dynamic 
> name-value pairs into the DB as well. I'm sure that there's a better way 
> to implement some parts of it, so please somebody review and clean up if 
> possible :)

The patch looks good on first read, but I'll have a closer look tonight,
and run a quick benchmark aswell, if all goes well.

Thanks!