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From Mage <m...@mage.hu>
Subject Re: CouchDB's advantages over MongoDB
Date Fri, 15 Apr 2011 14:13:33 GMT
        Hello,

I am new to CouchDB, coming from Postgresql (which doesn't mean I am
leaving PG). I never built anything on either MongoDB or CouchDB.

However I spent some time (two weeks maybe) to try and see the current
NOSql databases. I "tested" Cassandra, HBase, MongoDb, CouchDB and Neo4J
too. My tests were neither deep nor professional. I was just trying to
figure out which one to jump into.

And yes, they are very different. Finally I found myself thinking about
HBase and CouchDB. They are also totally different. I've chosen CouchDB
to learn.

The truth is that I wouldn't send my important data to MongoDB. And I
don't really send any non-important data anywhere.

MongoDB is not durable in my opinion. And in my test it wasn't even
stable, however that might be the fault if the client library I used.

I am using Gentoo amd64. Mongo version was 1.6 (there was not any stable
release for Gentoo amd64 that time). I used Rails 3.0.4 and gem
"mongo_mapper".

There were 97k records (users) migrated from a live, working
application, just copied from postgresql models to mongo_mapper without
any denormalization. Just for inserting something. Then I tried
delete_all (or destroy_all, can't recall) with MongoDB, which successed
in 1 second. Then I sent the very same command again to the
theoretically empty database. I pressed arrow up and enter. And I got an
exception from MongoDB or mongo_mapper. This should never happen.

My laptop has 4G ram, 4G swap on SSD. "Working" (well, I mean inserting
and deleting) with 97k records with MongoDB, mongo_mapper and Rails just
made the OOM Killer taking actions, several times. This was the point
when I said goodby to Mongo. Sorry, it might be my mistake, but too bad
for a first experience.

Again, I am not saying it was a native MongoDB fault, it could be the
client library too, however checking "top" command shown that Mongo is
eating the memory.

By the way, Postgesql or CouchDB is also very fast when installed into
ramdisk. This is how Mongo works.

For me MongoDB is something like MySQL. I think MySQL people will like
it. (Without starting any flame I would never use Mysql when it is
possible to avoid. And always is.)

For me CouchDB seems very exiting and fresh, something unique.

        Mage



On 04/14/2011 03:47 PM, Daniel Itaboraí wrote:
> I'm trying to come up with some of CouchDB's advantages over MongoDB. Mongo
> seems to have some advantages on easier "queriability" and overall speed
> (this is really an understatement, but I´m looking forward for the snappy
> compression and the NIF interface stuff).
>


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