Re: shre lock vs. exclusive lock

Ryan Gaffuri wrote:

> I am reading a standard university database textbook and I am
> attempting to apply it to Oracle. Here is the book... it's used all
> over the place
>
>
> http://www.amazon.com/exec/obidos/tg/detail/-/0072554819/qid=1081000904/sr=1-1/ref=sr_1_1/103-1148263-1387019?v=glance&s=books
>
>
> In the chapter on Locking it states that a share lock is used to lock
> on reads, so that other sessions can read, but cannot right. An
> exclusive lock is used on writes and no other session can access the
> data.
>
> Now oracle doesn't lock on reads and when it does writes, other uses
> can still read. So how does Oracle define share locks vs. exclusive
> locks in contrast to my book?
>
> Oracle's new search feature on metalink is hideous. I'd assume it's
> there, but I can't find it.

The book is giving you one academics view of something. High tech, and especially the RDBMS market, reuses common words. Thus you can not apply this definition, true for most databases, to all.

Look up the definition of the words 'block' and 'database' and you will find other words where the book doesn't come close to how it is used in the real world.

-- 
Daniel Morgan
http://www.outreach.washington.edu/ext/certificates/oad/oad_crs.asp
http://www.outreach.washington.edu/ext/certificates/aoa/aoa_crs.asp
damorgan_at_x.washington.edu
(replace 'x' with a 'u' to reply)