hi guys,
I found oracle documentation a really good resource to learn oracle. But I'm scared of it's lengthy documentation.
Now my question is: Should an oracle database user read all oracle documentation? If not, who will read all that? Great thanks.
No.
The documentation is intended for reference. Read the "2-day DBA", and then "Oracle Database Concepts". Read the rest as you go (as you use the features that they cover).
It's impossible to read all of the documentation that ships with many pieces of software nowdays. (Debian Linux, for example, ships with bookshelves worth of manpages). Focus on using the Oracle documentation as reference, read the parts that seem to be related to what you're doing, and look at 3rd-party books that may teach you what you need to know as well.
language documentation is not written to be a book to learn the language, but is written as a resource to reference as various questions arise...
Would you read a dictionary? An encyclopedia? This is a similar concept.
Nobody reads all the documentation these days. The important thing is to read enough of it so that you can find your way around the rest when you start to work on something new.
The Concepts Guide is a mandatory read. It gives a great overview of the database and its functionality, explaining some of the things which newcomers often find difficult to grasp (such as Oracle's approach to transaction management and isolation levels). It is also contains links to the relevant parts of the documentation which deal with these topics in depth.
Everybody ought to at least skim read the whole of the SQL Reference and the PL/SQL Packages and Types Reference, to get a feel for the range of Oracle's implementation. Reading these books in-depth will pay dividends.
DBAs should read the Administrator's Guide and the Backup and Recovery Basics; developers should read Application Developer's Guide - Fundamentals and the PL/SQL User's Guide. These books relate directly to your job, so skim read them only if your conscience will let you.
In recent versions the Performance Tuning Guide is not as useful as it once was, because it focuses too much on tools which require the purchase of additional licenses.
Which reminds me: everybody should read the Licensing Guide. Too often in forums like SO people are advised to use a feature or a package which requires a specific edition of the database or a chargeable extra (the most common thing in this category is Partitioning). The licensing information is pretty short, and reading it may just save your company from an embarrassing situation when Oracle's auditors come to call.
Tom Kyte has a useful "Road Map" to the Oracle documentation.
It can be found here.