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Comment by taligent | Hacker News Reader

I guess if only I "woke up" I would realise that PostgreSQL is the answer to all my problems. Guess what. PostgreSQL is just another SQL database. It's definitely one of the best ones but it still stuffers from all the same issues, limitations and frustrations. Many of which stem not from the database itself but from the relational modelling and tools to support it.

I use Java + MongoDB and life is significantly better now that I don't have to worry about the domain model so much. I can have lists, maps etc and can add classes or make changes seamlessly. It's worth the tradeoffs for me.

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I wouldn't call it just another SQL database. The extensible type system is actually really cool and you can do a lot with it, and the same goes for Listen/Notify. It's actually an application development platform in a box.

But I guess here's the flip side. PostgreSQL is another relational database and and that means fundamentally it operates on sets of tuples. For anything where set operations are helpful, the relational model brings something that no other models bring to the table. I doubt I will ever see a viable ERP suite written on a NoSQL system.

OTOH, there are plenty of areas where set operations are not that big of a deal. In this area, a networked, mostly reliable, multi-master replicated store of application state data is a really really cool thing. For example, imagine MongoDB as a backplane for an LDAP forest, replacing local BDB storage for something like OpenLDAP. The source data may be in a more mature data store somewhere and fed into MongoDB so if it gets lost it isn't the end of the world (just possibly some temporary business hicups). Same with, say, Root DNS root servers.

> Guess what. PostgreSQL is just another SQL database.

Uh... hstore says "I'm not quite sure what the bloody hell you're talking about". So does ltree.

Ahem, lists and maps seem a very easy thing to do in SQL. Where you get to the limits of the relational model is when three structure diversity is out of your hands, for instance a big bunch of parametrized messages.

Lists/Maps require extra tables which means more scripts, more migrations, more backups, more worry.

With MongoDB all I have to do is add Map<String,String> myMap to a Java class and that's it.

Actually, Postgres has had an Array data type since at least v8.0. http://www.postgresql.org/docs/8.0/static/arrays.html

But yes, you're right that maps require a join table.

> But yes, you're right that maps require a join table.

Not in postgres: http://www.postgresql.org/docs/9.1/static/hstore.html

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