Estelle DeBlois

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Recent posts by Estelle DeBlois

Rahul Babbar wrote:

Santosh Ramachandrula wrote:Rahul,
For your questions 1 & 2 please see similar issue at http://forum.springsource.org/archive/index.php/t-61016.html



Thanks for the above link, it indeed is the same issue.
However, the discussion(in the link) also does not seem to give a proper explanation as to why the query should be slower for the last set of records...

It could be a bug in some version of Oracle 10g or.....(well, i cant see any other reason... )



It's been a few months since somebody posted into this thread but I happened to wander through this and saw that the question as to why the query runs slower for the last set of records wasn't clearly answered... actually it was answered in http://forum.springsource.org/archive/index.php/t-61016.html but perhaps the last poster of this thread (Rahul Babbar) had missed it?

So here's my attempt at answering it with the little knowledge that I have. This article on "Ask Tom" explains it all: http://www.oracle.com/technology/oramag/oracle/06-sep/o56asktom.html (in particular, the section on Pagination using ROWNUM but you still have to read the whole thing to make the most sense out of it).

If you look at that query closely, you'll notice that it incorporates a top-N query (get the first :MAX_ROW_TO_FETCH rows from your query) and hence benefits from the top-N query optimization I just described. Further, it returns over the network to the client only the specific rows of interest—it removes any leading rows from the result set that are not of interest.



For the first page, your :MAX_ROW_TO_FETCH will be low (say, 20). Oracle will perform a top-N query using that value ("get me the first 20 results, sorted") then removes 0 leading rows since you're on the first page. If you're on the last set of pages, your :MAX_ROW_TO_FETCH will be much larger (say, 261159). You're only interested in displaying 20 results on your page, but Oracle still has to first perform a top-N query with the :MAX_ROW_TO_FETCH value ("get me the first 261159 results, sorted"); this takes much longer. Only afterwards will it discard the leading rows so you only end up with the 20 results to show on your page.
1. Question #37 of the Bonus Master Exam for SCJP 6 states that, among the statements that are true: "Both Currency and NumberFormat objects must be constructed using static methods."

Problem: The SCJP 6 Study Guide (K&B) never talks about the Currency class, only NumberFormat.getCurrencyInstance().

---------------------------

2. Question #7:

1. class Plant {
2. String getName() { return "plant"; }
3. Plant getType() { return this; }
4. }
5. class Flower extends Plant {
6. // insert code here
7. }
8. class Tulip extends Flower { }

Which statement(s), inserted at line 6, will compile? (Choose all that apply.)

Correct Answer
A: Flower getType() { return this; }
C: Plant getType() { return this; }
D: Tulip getType() { return new Tulip();

Problem: I chose A and C only because D is missing the closing curly brace... The system marked my answer as wrong.

---------------------------

3. Question #73:

[some code not shown here]

Correct Answer
B: Compilation fails due to a single error in the code.
C: Compilation fails due to multiple errors in the code.
E: By default, the readPassword() method echos the users keystokes.

References
EXPLANATION:
C, D and F are correct. The System class method is console() not getConsole(), and the
readline() method returns a String not a char[].
A, B, and E are incorrect based on the above.

Problem: The Correct answers and explanations don't match. If you check C, D, and F, your response will be marked "incorrect". However, clearly, there's a problem with the correct answers. How could you have both B and C at the same time anyway?




I hope the real exam doesn't actually have issues like these... (The one about Currency is debatable, but still, it would have been nice if it had been in the Study Guide).
Hmm, never mind. It was the quiz that I took, not the MasterExam (*sigh*). The quiz is only 90 min long for 75 questions, while the MasterExam is 210 min for 72 questions... Why such a difference, I don't know.
I've taken the MasterExam from the CD that came with the SCJP 6 Study Guide. Now, I am worried. According to the MasterExam description, "the number of questions, types of questions, and the time allowed are intended to be an accurate representation of the exam environment."

From the Sun website: http://www.sun.com/training/catalog/courses/CX-310-065.xml

# Number of questions: 72
# Pass score: 65% (47 of 72 questions)
# Time limit: 210 minutes

Now, I start up the MasterExam, and there are 75 questions, and only 1.5 hours to complete. I barely got past half of the questions when the time was already up. I'm very confused, because 1.5 hr is not even close to the supposedly allowed 210 min. That's not a very accurate representation of the exam environment now, is it? So which duration is correct? I'm guessing it is still 210 min for the real exam...