[openstack-dev] [Ceilometer] MySQL performance and Mongodb backend maturity question

Qiming Teng tengqim at linux.vnet.ibm.com
Thu Sep 25 08:12:15 UTC 2014


On Wed, Sep 24, 2014 at 09:43:54PM -0700, Preston L. Bannister wrote:
> Sorry, I am jumping into this without enough context, but ...
> 
> 
> On Wed, Sep 24, 2014 at 8:37 PM, Qiming Teng <tengqim at linux.vnet.ibm.com>
> wrote:
> >
> > mysql> select count(*) from metadata_text;
> > +----------+
> > | count(*) |
> > +----------+
> > | 25249913 |
> > +----------+
> > 1 row in set (3.83 sec)
> >
> 
> 
> There are problems where a simple sequential log file is superior to a
> database table. The above looks like a log ... a very large number of
> events, without an immediate customer. For sequential access, a simple file
> is *vastly* superior to a database table.
> 
> If you are thinking about indexed access to the above as a table, think
> about the cost of adding items to the index, for that many items. The cost
> of building the index is not small. Running a map/reduce on sequential
> files might be faster.
> 
> Again, I do not have enough context, but ... 25 million rows?

Yes, just about 3 VMs running on two hosts, for at most 3 weeks.  This
is leading me to another question -- any best practices/tools to retire
the old data on a regular basis?

Regards,
  Qiming
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