Re: Microsoft destroys TPC-C records!

From: Norris <jcheong_at_cooper.com.hk>
Date: 6 Apr 2000 01:33:20 GMT
Message-ID: <8cgph0$2bv3$1@adenine.netfront.net>

Thanks for your point of view. Sorry for my poor english.

Here is my understanding from the manual:

Oracle offers the read committed and serializable isolation levels, as well as a read-only mode that is not part of SQL92. Read committed is the default and was the only automatic isolation level provided before Oracle Release 7.3.

Oracle automatically provides read consistency to a query so that all the data that the query sees comes from a single point in time (statement-level read consistency).
Oracle can also provide read consistency to all of the queries in a transaction (transaction-level read consistency).

Oracle never escalates locks. Lock escalation greatly increases the likelihood of deadlocks

Locks Obtained By DML Statements

DML Statement Row Locks? Mode of Table Lock

SELECT ... FROM table

INSERT INTO table ...     X          RX
UPDATE table ...          X          RX
DELETE FROM table ...     X          RX
SELECT ... FROM table ... X          RX

FOR UPDATE OF ... LOCK TABLE table IN ...

ROW SHARE MODE                       RS
ROW EXCLUSIVE MODE                   RX
SHARE MODE                           S
SHARE EXCLUSIVE MODE                 SRX
EXCLUSIVE MODE                       X
--------------------------------------------------------

X: exclusive
RX: row exclusive
RS: row share
S: share
SRX: share row exclusive

In comp.databases.sybase DNP <High.Flight_at_btinternet.com> wrote:
> David P.
> Oracle Certified DBA.
> ======================================================================

> Then last but not least, why don't you study Oracle's locking model
> before demonstrating your ignorance one more time?

> There's nothing more tiresome than an argument where one person is not
> prepared to listen to the others point of view.

> Then when you have learned to do that, why don't you consider
> intelligently joining in this discussion?
Received on Wed Apr 05 2000 - 20:33:20 CDT