I agree that the relative small size of PostgreSQL documentation and the fact that it fits in a single "book" compared to the many books that comprise the Oracle documentation can make it easier to find something. But can't say I've ever seen a product with as much quality documentation as Oracle.
You can find the documentation for Oracle 12c here: http://www.oracle.com/pls/db121/homepage
As a user, you want to look in "SQL Language Reference" first, followed by "Data Warehousing Guide" (found in a separate folder on the left side). As an administrator, "Concepts" is required reading followed by "Administrator's Guide".
I'd generally agree that Oracle's documentation is more extensive than PostgreSQL's in many respects, but Oracle's is also substantially less well organized than PostgreSQL's.
Reference?
http://www.postgresql.org/docs/9.3/static/functions-aggregat...
Not only as an example of "single line in a table" but also as an example where a huge volume would not add much value.
I'm struggling at this time to figure out how to produce multiple pages of boilerplate explaining "min()" that would be any more useful than the table.
On the other hand the explanation about nulls really sucks. Its important enough to put in the single line. For those too lazy to click and read, when a noob thinks he wants "SUM(bunchastuff)" what he probably wants is along the lines of using COALESCE or a homemade function that smells like COALESCE. There is a meta discussion that whenever NULLs are possible, and its more than just table definitions for example an overactive WHERE clause, then the NULLs will be a PITA. Defensive SQL coding can be tedious.
That was a bit tongue-in-cheek... Oracle makes an exceptionally solid RDBMS and deserves credit for that. It's just that it hurts every time I write VARCHAR2.