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On Thu, Sep 25, 2014 at 11:51:23AM -0400, gordon chung wrote:
> > mysql> select count(*) from metadata_text;
> > +----------+
> > | count(*) |
> > +----------+
> > | 25249913 |
> > +----------+
> > 1 row in set (3.83 sec)> 
> > There were 25M records in one table.  The deletion time is reaching an
> > unacceptable level (7 minutes for 4M records) and it was not increasing
> > in a linear way.  Maybe DB experts can show me how to optimize this?
> we don't do any customisations in default ceilometer package so i'm sure there's way to optimise... not sure if any devops ppl read this list. 
> > Another question: does the mongodb backend support events now?
> > (I asked this question in IRC, but, just as usual, no response from
> > anyone in that community, no matter a silly question or not is it...)
> regarding events, are you specifically asking about events (http://docs.openstack.org/developer/ceilometer/events.html) in ceilometer or using events term in generic sense? the table above has no relation to events in ceilometer, it's related to samples and corresponding resource.  we did do some remodelling of sql backend this cycle which should shrink the size of the metadata tables.
> there's a euro-bias in ceilometer so you'll be more successful reaching people on irc during euro work hours... that said, you'll probably get best response by posting to list or pinging someone on core team directly.
> cheers,gord 		 	   		  

Thanks for the responses above.
TBH, I am unware of any performance problems based on my previous
experience using MongoDB as the backend.  I switched over to MySQL
simply because only SQlAlchemy has supports to Ceilometer events.
Sorry for the confusion -- the metadata table size wasn't a direct
result of using events, though it does seem like an indirect result of
switching to MySQL (not sure about this either).

I'll try Euro work hours in future.  Thanks for the hints!

Cheers,
Qiming

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