On 08/01/16 19:07, Nicolas Paris wrote:
> Hello Mark,
>
> As far as I know, MongoDB is able to get better writing performances
> thanks to scaling (easy to manage sharding). Postgresql cannot (is not
> designed for - complicated).
> Why comparing postgresql & mongoDB performances on a standalone
> instance since mongoDB is not really designed for that ?
Yes you can get better performance with mongo via the sharding route but
there are a number of quite bad downsides to mongo sharding - limited
ability to perform aggregation, loss of unique key constraints other
than the shard key, requires at minimum 4-6* the hardware (2 replicas
for each block = 4 + 2 * mongos gateway servers)... Actually pretty
similar to the issues you see when trying to scale a RDBMS via
sharding... We tried doing some mongo sharding and the result was a
massive drop in write performance so we gave up pretty quickly...
Mark