The following is a video presentation about how Oracle Coherence capabilities function, such as in-memory caching, dynamic data partitioning, and parallel query and process execution.
Comments Off | Filed in Oracle | Tags: coherenceI was recently elected to the Board of Directors of the Northwest Oracle Users Group (NWOUG). My official title is: membership coordinator, which means that I will be responsible for monitoring and maintaining the NWOUG membership database, answer members’ questions, send out email communications and follow-up on expired memberships, among other things. And, to bring it to the web 2.0 age, I have created the NWOUG mix group and wiki page.
Being a member of an Oracle users group can be useful. For example, NWOUG:
But, other than the things I mentioned above, what is the added value of joining an Oracle users group? especially with the abundance of freely available information on the Web. Whenever I think about it, I always come back to the same conclusion. I believe that the most value of being a member of a users group are the people you meet during these group events, the face to face interaction, the referrals and experience sharing.
It’s that socializing and communicating with people, who share the same interests as yours, what makes joining a users group in general, and an Oracle one in particular, worthwhile. Don’t you agree? What users group are you a member of? What do you think a users group should do to justify its existence and value to its members?
7 Comments | Filed in Oracle | Tags: usersgroupHere is something interesting. Oracle converts this outer join query
SELECT T1.d, T2.c
FROM T1, T2
WHERE T1.x = T2.x (+) and T2.y > 5;
and its ANSI equivalent
SELECT T1.d, T2.c
FROM T1 LEFT OUTER JOIN T2
ON (T1.x = T2.x)
WHERE T2.y > 5;
into this inner join query
SELECT T1.d, T2.c
FROM T1, T2
WHERE T1.x = T2.x and T2.y > 5;
That’s according to the Optimizer Development Group blog. They go on to explain:
Here the filter predicate on the outer-joined table T2 does not contain the outerjoin operator (+); thus it will be applied after the left outerjoin has taken place. This will result in the elimination of all null appended rows of T2. Hence, Oracle converts the outer join into an inner join.
And here is an interesting thing about ANSI full outer joins:
Before Oracle 11gR1 all ANSI full outerjoins were converted into a UNION ALL query with two branches, where one branch contained a left outerjoined lateral view and the other branch contained a NOT EXISTS subquery. A native support for hash full outerjoin was introduced in 11gR1 to overcome this problem. When the native full outerjoin cannot be used, Oracle reverts to the pre-11gR1 strategy.
Their latest blog post about Outerjoins in Oracle is a good read.
1 Comment | Filed in Joins, Oracle | Tags: concepts, joinHere is the second episode of Oracle in 3 Minutes. I titled it A Ticking Bomb, but you can also call it A Sleeper Bug.
6 Comments | Filed in Oracle | Tags: 3minoracle