The oracle databases i've used are in the order of 1Tb with several tables of 55m+ rows. The main thing you really have to be careful of is the way you construct your queries, rather than how you execute them via perl. Make sure you make use of explain plan to tune your queries, especially if your data is "worthy".

The main down side with Oracle is the damn cost. Its *really* expensive. Cost aside, it does scale very well, there are lots of resources out there for it, from skilled professionals, to tutorials, to a very active community.

After a little research, I chose postgres over mysql maily because of the transaction based approach. I use it on my desktop for some web stuff, information management and generally small stuff. I've also used postgres as a base to develop some Oracle web apps. Some of the stuff requires some small changes (ie the date functions, O=sysdate P=now(), and the table creation stuff wrt specific datatypes, constraint syntax et al)... All very minor stuff.

Postgres as survived being thrown across harddisks, disk failures and reinstallations, without losing a byte of data. I must say I treat it pretty badly, and has survived very well. Given the stability and the cost (free) it was a real boon for me to get/use and learn.

As most people have already said, your question could be better rephrased as, "Which database is the best for me?". The only thing I say, would be it must be SQL 92 complient (or use it as a base). I say this becuase, you dont want to go down the road of learning (or inventing) some vendor specifc language (if you choose an RDBMS)

I dont know if anyone has mentioned OLAP databases here yet. There are a couple out there, Oracle Express, Essbase, however i'm not sure of their interfacability to perl. I've mentioned them because they work really well with specific types of data. For example, i've used Essbase for financial type data (management and financial accounting). Altho' i didnt use perl, they suited the data perfectly.

I guess the point is keep an open mind. Perl/RDBMS may not be the answer to your problem.