Comment by rgo | Hacker News Reader

Comment by rgo | Hacker News Reader

Previous versions of my startup's enterprise product used to be based on relational DBs (mostly Oracle, MySQL also). This year we switched to Mongo and dropped RDBMS support.

RDBMS performance was fine most of the time as we're not doing big data really. Our problem was developing and maintaining a schema that holds lots of metadata many levels deep. Our app allows for unlimited user defined forms and fields, some of which may hold grids inside which hold some more fields... Our app also handles lots of logs and large file dumps, which slowly made data, cache and fulltext search management mission impossible. Even though we had considerable previous experience with Mongo, it took us a long time to switch because we were utterly scared. It's nice to sell a product that is Oracle-based, as that sent out a message about our "high-level of industry standardization and corporate commitment" bullshit that (we thought) is quite positive for a startup competing against the likes of IBM, HP, etc.

To our surprise, our customers (some Fortune 500 and the like) were VERY receptive to switch to a NoSQL, opensource database. Surprise specially given it would be supported by us instead of their dreadfully expensive and mostly useless DBA departments. It even came to a point where it has changed their perception of our product and our company as next generation, and surprisingly set us apart from our competition even further.

In short, as many people here know, not all MongoDB users are cool kids in startups that need to fend off HN front page peak traffic day in day out. Having a schemaless, easy to manage database is a step forward for sooo many use cases, from little intranet apps to log storage to some crazy homebrew queue-like thing. 10-gen superb, although criticized, "marketing effort" also helps a lot when you need to convince a customer's upper-management this is something they should trust and even invest on. I can't express my gratitude and appreciation for 10-gen's simultaneous interest in community building, flirting with corporate wigs and getting the word out to developers for every other language. Mongo is definitely a flawed product, but why should I care about the clownshoeness of its mmapped files when it has given us so much for so long?

Well written post. Even as a detractor of mongo I'll agree that it works for your use case. But the key is "Our app allows for unlimited user defined forms and fields, some of which may hold grids". That really isn't a very common case. SQL is not great at representing large groups of documents without any common structure.

The vast majority of apps just don't deal with that problem. If MongoDB was really only used by people that its a good fit for (like yourself), it'd really be a niche product. They're marketing it as a general purpose product, which is why they've earned scorn from so many.

Bingo. They should call themselves mongodocs, not mongodb. The way I see it mongodb sees widespread misunderstanding about its use cases and instead of make the use cases more clear, they seem to take an interest in seeing mongodb being used unnecessarily.

> Having a schemaless, easy to manage database is a step forward for sooo many use cases

Can you explain why can't you do schemaless with an RDBMS?

From what I understand MongoDB is schemaless by storing all fields as one single JSON document. So what stops you from doing the same in an RDBMS - have a catch-all field "JSON" and store all your data there?

That gets you halfway there, but you still don't have the ability to query your datastore by structure, unless you've installed PostgreSQL 9.3 and are using its JSON field type, which does have that capability, thus entirely demolishing the NoSQL USP as far as I can determine.

That is awesome.

Also of note is that stored procedures are supported in a variety of languages, including Javascript, so it's quite easy to handle cases where the surprisingly broad range of core JSON functions and operators [1] doesn't include what you need.

PostgreSQL has also recently added a key-value store type [2] with semantics reminiscent of Redis. The impression I get is that they're gunning for the NoSQL kids in general, and this pleases me; while I grant it is sometimes possible and necessary to obtain new insight in a field by ignoring all that's gone before, I very much doubt this is one of those times, and I am therefore delighted to see a properly engineered database engine gain more or less the entirety of the features which draw interest to the NoSQL crowd in the first place.

[1] http://www.postgresql.org/docs/9.3/static/functions-json.htm... [2] http://www.postgresql.org/docs/9.3/static/hstore.html

That is extremely interesting. So it looks like you can store a JSON type as well as a KV datatype in Postgres! And it looks like it is relatively easy to convert between the two.

This leaves only performance. I think I'm still confused around this area - why do people say that non-relational technologies like MongoDB are faster than relational databases?

That'd be an unqueryable string field in most sql databases. Not at all the same thing.

Thanks for sharing your experience on this. We make a lot of custom enterprise intranet applications, and we've been considering adding MongoDB to our toolchest. My concern has been what you say- there will be customer resistance. That they'll have fear for the future of their DB, since it's not SQL. Based on your post, it seems like it may be my fear and not necessarily the clients'. I was very interested in NoSQL at the beginning and what that did is make me realize I need to up my SQL game. I want to make sure I don't move into NoSQL just because it's hip and relational DBs annoy me.

We are evaluating Mongo to be the persistence for single page web applications, which is how we'd like to start making the majority of our intranet/private enterprise jobs. Are you using it in this context and has it been helpful? Your example of nested fields being easier made me warm and fuzzy- we had a project last year that had growing, fluid, user-defined data structures. We made it work (well) with Postgres but there were several kludges that really bothered me. One of them was handling delete dependencies gracefully on user-defined, nested structures. Did you encounter this issue pre-Mongo as well and if so, did it help with it?

Perhaps your customers were receptive because you were supporting it and they were happy with the existing support you got and unhappy with their internal DBA department? Its possible that they didn't care about the technology and just realized that the support was going to be better.

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