Subject: Re: How we made Postgres upserts 2-3* quicker than MongoDB
To: Nicolas Paris <niparisco@gmail.com>
References: <568FE5D0.9040901@allaroundtheworld.fr>
 <CA+ssMOS9FCk-bn5WY0ctHMGOEu612HDsODytOB-qSLmbh9v-TQ@mail.gmail.com>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
From: Mark Zealey <mark@allaroundtheworld.fr>
Message-ID: <568FEEF2.2030603@allaroundtheworld.fr>
Date: Fri, 8 Jan 2016 19:16:34 +0200
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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


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