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Comment by jacques_chester | Hacker News Reader

I think the main revelation in databases was the division of the world into OLTP and OLAP.

So you keep your normalised schema for production and have a methodologically denormalised schema for reporting.

Mind you, computer science courses generally don't teach OLAP -- stuff like dimensional modelling. My university didn't when I was there, though they've rolled it into a larger "Data Mining" course alongside MapReduce and friends.

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Agree. & this makes sense from an architectural perspective, since the demands of each domain are different.

I was arguing from practical terms and my own experience. Even in established, DB-heavy, "we have hundreds of DBAs" organisations, you can't have a porcelain schema. It evolves over time, breaks, get optimised and de-optimised.

The Oracle shops I've worked in don't have one schema, they'll have dozens. Usually because they can't shoehorn emerging requirements into the databases they have. Or because of project timelines. Or they need to be performance tuned in some special way, which in the case of Oracle could be considered a dark art.

These orgs may have just one big data warehouse, but that becomes a dumping ground. It's possible to do your dimensional modelling (I worked on star schemas in the past, but that's about it) -- but it's a big ball of mud to try and weave together.

Even then your OLAP is under-stress because it's got a lot of ground to cover. Usually they start out as marketing engines, but get co-opted into all sorts of things. The most common and troublesome is regulatory reporting. Once your data warehouse gets used for something like regulatory reporting you're a bit stuck as nobody wants to touch it.

Then, because point to point integrations between the databases is brittle and cost-prohibitive -- they break the golden rule and take data out of the OLAP and put it back into the OLTP. I won't name names, but this is commonplace.

SalesForce is one of the biggest Oracle DB users (I read biggest at one stage, but can't find the reference). Even then the SalesForce data model is so denormalised you could call it one big table[1].

I use MongoDB day-to-day and it's fit for purpose for what I do. That said, I'm not a rabid fan and an alternative/hybrid approach is always on the horizon. What I don't buy is the "the DB world has already solved all these problems", particularly when things like "relational integrity" and "two phase commit" get thrown in the mix - truth is there is plenty to be solved.

[1] http://www.dbms2.com/2011/09/15/database-architecture-salesf...

Does using a document store solve any of these problems, though?

In some limited ways. I don't think the technology and lines of approach are fully mature yet.

I don't know any MongoDB users that I think would be better off on Oracle - especially for the reasons cited in the article.

My own view is the critical pieces will converge. If I could have PostgreSQL with a greatly simplified replication/parallelisation solution I'd be a happy man.

Equally if MongoDB could do a COUNT query in even double the time of psql. Or compress their keys. Or have fine-grained locking... (All of which I'm sure they will get to, just when).

Maybe that's MongoDB 5, PostgreSQL 14, Rethink 3 - I've got no idea and I'm sure I'll look at them all. However, I'm not the guy rocking up to a MongoDB conference and coming away with the conclusion "Oracle had that in 1988".

Once you start adding all those features in, the performance you gained by not doing them evaporates. That is the lesson of MySQL.

My argument is not that MongoDB users would be better off on Oracle. It's that Oracle users would not necessarily be better off on MongoDB, since Oracle actually does many things that the makers of MongoDB claim it can't. If MongoDB had been made by MS, everyone would call that "FUD"...

So we stop trying? The contribution of MySQL to the world of databases is significant.

If your intent is to rebut FUD, then statements like "But just remember that these kids think they’re solving problems that IBM (et al) solved quite literally before they were born in some cases" don't contribute. You're just meeting rhetoric with rhetoric.

If by "trying" you mean, random coding expeditions performed by people in too much of a hurry to find out what their forebears discovered, then yes, you stop trying. You stop trying and start reading, start researching, start thinking. There are vast reserves of knowledge just sitting there in the source code, waiting to be read. Looking at the CAP theorem and deciding to make a distributed database to exploit different tradeoffs is very sensible, but hubristically ignoring everything that came before because it's older than a decade is not.

You'll have to be more specific if you want to have a real discussion. Calling MongoDB a random coding expedition doesn't give me anything to go on, except perhaps just to flame back. Same goes with "ignoring everything". It's an absolutist statement that is patently false.

If there is something specific that MongoDB is blatantly or arrogantly ignoring from Oracle (i.e. the original article) -- technical, business model, whatever -- Then call it out.

I (obviously) disagree. Reinventing the wheel is fun, we all do it. But (to stretch an analogy), if there have been cars for decades, and you claim to have just invented the wheel, and that all previous wheel were square, then I would ask what you (think you) have accomplished - why not a) make a better car and b) tell us why your car is better. If the MongoDB schtick is "we can do 10% of what Oracle can for 1% of the price" then that's great, there is a real market for that (assuming that 10% overlaps with the 10% of Oracle that you happen to use).

I was using MySQL for real work back in the 1990s. I remember then, them saying, you don't need foreign keys - just check it in your application. You don't need transactions either, just handle failures in your application, yadda yadda. And of course, MySQL these days supports all these things (with InnoDB, an Oracle product) because these things weren't there "for lulz" in commercial databases, they were there because people needed them and saw value in them. Now I am getting a complete sense of deja vu with MongoDB. It will have to add transactions. This is inevitable. It will have to add enforced schemas, row level locking, ACLs, and other features besides. If we remember, then in a year, let's touch base again, and you'll see I'm right. This is what I mean when I say the lesson of MySQL.

And in 10 years, there will be another product, let's call it ZongoDB, and the cycle will repeat again. You don't need this, you can't do that, they'll say, and the MongoDB crew, by now themselves old geezers (this means, in IT, in their 30s) will roll their eyes.

PS I may be an Oracle partisan, but I recognize too when Oracle implements something IBM did back in the 70s...

TokuMX adds compression, fine grained locking, and a lot more to MongoDB. It's a version of MongoDB with the storage code replaced with the same storage core as TokuDB.

Thanks. I'd read about the fractal tree indexes, but not the rest. I'll take a look.

In the 90s, we had "document stores", except we called them object databases.

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