Is MongoDB object-oriented?

[Jerseyfoo]

I can't seem to find any indication that MongoDB can do this
natively...

db.posts[26].author --> db.users[3]

[Andreas Jung]

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This has nothing to do with object-orientation.

MongoDB is a *document* database. Also the low-level API does not
provide any special OO support. Object-mappers like Mongokit for Python
sitting on top of the language dependent driver can provide an
OO-oriented API.

- -aj
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[Sam Millman]

Depends on the driver. In PHP it is. All OO inheritance within Mongo tends to occur within the drivers themselves and not the DB due to the type of DB this is.

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[Andreas Jung]

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Sam Millman wrote:
> Depends on the driver. In PHP it is. All OO inheritance within Mongo
> tends to occur within the drivers themselves and not the DB due to the
> type of DB this is.

An object-oriented API is different from having an object-storeage or an
object-oriented database - MongoDB is basically a JSON storage.

- -aj
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[Sam Millman]

True but one of the main benefits of JSON (over XML) is that it can store objects in Object form (I do in my REST servers all the time). So it is possible to have a OO storage...in a strange twisted way.

It is also why it is possible for a driver to possibly abstract OO from Mongo....but I don't know enough of the low level API and you know more than me.

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[Tim Hawkins]

there was some discussion about layering an object factory into the driver, so that it could instance a object with attached methods around the data in the document, but it was decided that was best left outside the driver.

OODBMS system have the same problem, somewhere the methods for an object need to be defined, and that code needs to be bound somewhere, that is generally in the application.  The apps usualy have a factory that makes objects from the stored data, and binds the methods to them. 

Most OODBMS systems also cant store the methods, at best they can provide metadata that would allow a factory to recreate objects. 

[Jerseyfoo]

Essentially, MongoDB is just a replacement for SQL. Very
disappointing.

>This has nothing to do with object-orientation.

if a database cannot do that, it's not a object-oriented database.
It's not about what API you use, the data needs to be stored object-
oriented, or the performance will be terrible.

>Most OODBMS systems also cant store the methods

Methods are in the source, do you store your code in the database?
OOP is structured.

db.topics[id].posts[0].author.displayName == db.author[7].displayName

Think about it.

[yatesco]

Wow - some big statements you are making there!

Essentially, the only thing that you have asked for that is missing is
the enforcement of relationships - MongoDB being a *document* database
makes no claim in supporting inter-document relationships (although it
will perfectly happily persist embedded documents).

Claiming that MongoDB is just a replacement for SQL is so far off the
mark that it makes me think you haven't really read (or know?) much
about this area. They are two completing different beasts and are not
inter-changeable in anyway whatsoever. Sure, they both do storage and
querying, but if I spent 10 minutes writing a framework which
serialises and loads things from disk, would you claim that is a
replacement for SQL just because it doesn't understand inter-document
relationships?

<rant>
The problem is that relational theory and RDBMS immediately place you
in a restricted area where a very small number of paradigms exist.
You are pretty much forced to restrict your persistence to fit in with
their (very limited) capabilities. The NoSQL movement comes it from
the other end of the spectrum - you can do pretty much whatever you
want, store things however you want (with the caveat that you need to
do some of the heavy lifting) and all of a sudden people are at a loss
because their technology choices are no longer forcing them down a
narrow path - they now have choice and are forced to address that
responsibility. Which is a scary thing indeed!

To be clear - I love SQL and have been using it for years and it sits
along side MongoDB in my current application. Different tools for
different jobs.
</rant>

Hmmmm.

[Andreas Jung]

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yatesco wrote:

>
> <rant>
> The problem is that relational theory and RDBMS immediately place you
> in a restricted area where a very small number of paradigms exist.
> You are pretty much forced to restrict your persistence to fit in with
> their (very limited) capabilities. The NoSQL movement comes it from
> the other end of the spectrum - you can do pretty much whatever you
> want, store things however you want (with the caveat that you need to
> do some of the heavy lifting) and all of a sudden people are at a loss
> because their technology choices are no longer forcing them down a
> narrow path - they now have choice and are forced to address that
> responsibility. Which is a scary thing indeed!
>
> To be clear - I love SQL and have been using it for years and it sits
> along side MongoDB in my current application. Different tools for
> different jobs.
> </rant>

Nothing to be added except that I am under the impression that
a lot of people are using blindly using MongoDB for whatever
reason - without reflecting what they are really doing and without
thinking whether MongoDB is the right tool for a particular task or not.
MongoDB is not universal multiple-purpose devices for all problems...
it's "just" another valuable tool among others in the programmer's toolbox.

My 2 cents,

- -aj
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[Sam Millman]

"Claiming that MongoDB is just a replacement for SQL is so far off the
mark that it makes me think you haven't really read (or know?) much
about this area."

I've actually found it as a more than satisfactory replacement. As Andreas states it is all in the use case though I understand what you mean :P.

"Essentially, MongoDB is just a replacement for SQL.  Very
disappointing."

Well then you obviously dunno nosql. Should have looked up the term in wikipedia first.

"if a database cannot do that, it's not a object-oriented database.
It's not about what API you use, the data needs to be stored object-
oriented, or the performance will be terrible."

From what I know mongo does a heck of a lot from the API (and JSON can store objects just like I said). If it can map/reduce massive collections with ease and faster than a small join in SQL I'm pretty sure OO would be a walk in the park for it.

"db.topics[id].posts[0].author.displayName == db.author[7].displayName"

With positional operators and a map reduce I think I could do a query based around that....since that is just accessing arrays...think of docments as arrays and subdocuments as arrays in arrays...I'm not actually certain of what your trying to do now. Yes in SQL something like that would require an OO inteface but Mongo works differently and that query would be inert because thats not how you layout your nosql schema.

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[Ethan Gunderson]

You know what's funny? You could replace MongoDB with MySQL or Postgres, and that paragraph would still be true :)

Most developers have a nasty habit of defaulting to a certain technology stack, and applying it to all problems without any real analysis of their problem space. This problem does not solely exist in the Mongo community.

/rant

-Ethan

[Andreas Jung]

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Ethan Gunderson wrote:
> You know what's funny? You could replace MongoDB with MySQL or Postgres,
> and that paragraph would still be true :)
>
> Most developers have a nasty habit of defaulting to a certain technology
> stack, and applying it to all problems without any real analysis of
> their problem space. This problem does not solely exist in the Mongo
> community.

Absolutely true - I can only agree.

As former Zope release manager and core developer I am using the ZODB (a
true object database/storage) for more than ten years.

During that time a lot of other developers considered the ZODB as "the
tool" for all-and-everything. The basic problem here is that a bunch
of "developers" don't have enough background and insight in basic
foundations of programming and computer science.

Andreas

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