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

Preston L. Bannister preston at bannister.us
Thu Sep 25 04:43:54 UTC 2014


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?
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