• Assignment 2 stats and your marks

    Posted by Raymond Wong Monday 03 May 2021, 10:32:35 PM.


    423 submissions.

    After auto-marking:

    115 students = 10/10

    191 students >= 8/10

    Median = 7.8/10

    Mean = 7/10

    ~70 students =< 5/10

    ~11 students had correct queries but wouldn't even pass the previously provided sanity test due to various formatting issues*

    * We are manually checking & marking these queries. Instead of zero marks, partial marks (with 30% penalty) will be awarded to each of the tests if the formatting issues are minor.

    Finalized marks (after auto-marking, manual checking of *, and late penalty adjustments; and then scaled to 20) will be available in SMS from tomorrow afternoon.

  • Assignment 2 auto-mark tests

    Posted by Raymond Wong Monday 03 May 2021, 10:13:22 PM.

    You can check your assignment 2 performance by running the auto-mark test script at


    Make sure your submitted files (msearch toprank shortest) are in the current directory.

  • Exam submission via command line

    Posted by Raymond Wong Friday 30 April 2021, 05:12:14 PM.

    I've tested the exam submission via webcms and it's still shaky. I have disabled the webcms submission.

    As mentioned in the previous email, please use the command-line instruction:

    give cs3311 exam ans.sql ans.txt

    to submit your answers.

    Note that "give" is available on CSE machines except grieg .

  • Final exam information

    Posted by Raymond Wong Tuesday 20 April 2021, 05:26:25 PM.

    You can find detailed information here .

    I will go through it and answer any questions in the live session tomorrow.

  • Tut this week

    Posted by Raymond Wong Monday 19 April 2021, 05:52:00 PM.

    The tut this week is your last chance to ask your tutor any questions related to tute exercises (or lecture topics) before the exam. You are highly encouraged to attend.

  • Quiz 7

    Posted by Raymond Wong Friday 16 April 2021, 06:03:04 PM.

    Due to the CSE home directory incident, Quiz 7 due date has also been extended to 23:59 Monday, April 19.

  • CSE home directory issues (resolved)

    Posted by Raymond Wong Friday 16 April 2021, 05:21:26 PM.

    I have been informed by ss that you can now log in to CSE machines and resume your assignment work.

    If your home directory has been affected by this issue (all files disappeared), please follow the instructions to restore (using tkrestore). If you have problems using tkrestore to retrieve your missing files, you need to contact Helpdesk told me that they will be around after hours and during the weekend as well.

    If your home directory has been restored successfully, and you experience this issue again from now on, please email and copy cs3311.

    Again, if you have further questions regarding this issue, please post to the webcms Forums.

    Reminder: the extended assignment deadline is now: 5pm Monday, Apr 19, 2021 AEST.

  • CSE home directory issues

    Posted by Raymond Wong Friday 16 April 2021, 11:50:22 AM, last modified Friday 16 April 2021, 12:05:39 PM.

    Dear COMP3311 students:

    There have been home directory issues affecting a small group of students and I have been communicating with them until 4am this morning. However, the problem is still ongoing. CSE system support has been tracking all activities but will need you to stop working on the assignment from now until 5pm today (I will keep you updated if there are any changes).

    I have more than 100 emails related to this issue received this morning. If you have sent me one or a few, it's unlikely that you will receive my reply individually. So what I would like to ask you to do is:

    1. Stop logging into CSE machines and stop working on your a2 now until 5pm today (and check WebCMS Notice around 5pm).

    2. After 5pm, if you need to restore your missing files, follow the instructions of Robert's email in the notice below. If you have problems to restore the files, contact helpdesk@ cse as Robert suggested. Please do not ask cs3311 how to fix the problem. It is beyond our access privileges to fix / do anything for you. It has to go to ss.

    3. The a2 due date will be extended to April 19 Monday 5pm for ALL students . I will update the give submission system shortly.

    If you have further questions, please post to the Forums.

    Regarding this issue, only email cs3311 or me unless it is necessary. Thanks for your assistance and I apologise for the inconvenience.

  • The email from ss

    Posted by Raymond Wong Friday 16 April 2021, 02:42:40 AM.

    Some students told me that they have not received any emails from Robert (ss@cse). I'm posting his email here:

    Dear CSE Students,

    Roughly thirty CSE students have noticed this evening that their CSE
    home directories have been emptied.

    The CSE Computer Administrators are working to find the cause of this
    problem and stop it happening. For now more people are reporting this
    problem, so we do not think it has stopped happening, yet.

    It has only happened to a small proportion of the people who logged
    into a CSE computer this evening.

    If this happens to you, you may notice that your CSE desktop resets to
    default when you log in. Almost all of the files will have gone from
    your CSE home directory.

    If you have lost assignment files, you should tell your tutor or
    lecturer about that.

    Backups of CSE files are made every night, so you can get back a copy
    of your files from yesterday, if you need them. See:<wbr>FAQ/Restoring_files_from_backu<wbr>p/

    If you need assistance with restoring files, or resolving other
    technical problems you should send an email to:

    If you observed anything unusual happen before you lost your CSE files,
    please tell us about that too.


    If this has not happened to you, now is a good time to make an extra
    copy of any important files in your CSE account. You might copy them to
    your home computer, or your UNSW file space which, on CSE computers is
    at: /unsw/<zID>
    (See:<wbr>FAQ/UNSW_File_System/ )

    Yours Sincerely,
    Robert Doran
    for CSE Computer Support

  • Issues on some CSE home directories

    Posted by Raymond Wong Friday 16 April 2021, 01:39:40 AM.

    You have all received an email from Robert (ss@cse) that some CSE students have noticed this evening that their CSE home directories have been emptied. SS is currently logging and tracing the activities on CSE machines and investigating the issue. If this has happened to you, please restore your files from the every night backup by following the instructions described in his email.

    Please also email with a screenshot of the issue. We may not be able to quickly respond, as we have been receiving lots of emails. We will pass your ziD and details to SS for their investigation. If you have been affected by this issue, you will be granted a 48-hours extension (i.e., due on Sunday 5pm).

  • Brute force queries on CSE

    Posted by Raymond Wong Wednesday 14 April 2021, 07:23:49 PM.

    ss@cse has informed us that there are some extremely huge, brute-forcing queries creating massive sqlite3 tempfiles on CSE machines.

    Before you run these queries, could you please set the following:

    set TMPDIR=/tmp

    There is more space in /tmp. Otherwise, they may have to terminate those running processes.

    Thank you.

  • Live session this week (again)

    Posted by Raymond Wong Tuesday 13 April 2021, 02:01:33 PM.

    There have been a few questions regarding a1 marking in the forum. I will further explain and go through a few examples of why your solution failed the autotests this week.

  • Live session this week

    Posted by Raymond Wong Monday 12 April 2021, 04:56:08 PM.

    In addition to relational algebra, in line with the topics this week, I will use the a2 movie database as an example to discuss SQL / Python performance tuning.

  • Test scripts for a1 and a2

    Posted by Raymond Wong Wednesday 07 April 2021, 08:20:24 PM.

    The fd and normalization exercises used in the live session are now available at Slides and Videos .

    As shown in the live session this evening, a simple bash script, as a sanity check, for a2 formatting check is available. It doesn't perform any serious testing. So you should still test the correctness of your programs. To run the script, simply go inside the folder that contains your Python programs and type


    Furthermore, you can check your assignment 1 performance by running the auto-mark test script at


    Please watch today's live session recording if you have questions regarding the test scripts above.

  • Quiz 5 reminder

    Posted by Raymond Wong Thursday 01 April 2021, 03:47:39 PM.

    Please complete quiz 5 today if you do not plan to work on it on Easter Friday. Happy Easter!

  • Assignment 2 Spec

    Posted by Raymond Wong Tuesday 30 March 2021, 03:24:55 PM.

    Assignment 2 spec is available. It is due on Friday 16th April 5:00pm AEST.

    Please read the spec carefully before you start.

    I'll go through the spec in detail (and answer any questions) during the live lecture this Wed 4-6pm.

  • Quiz 4

    Posted by Raymond Wong Friday 19 March 2021, 05:58:18 PM, last modified Friday 19 March 2021, 05:59:20 PM.

    For those who have not completed Quiz 4, please be reminded that it is due tonight.

  • The trigger example from the live session

    Posted by Raymond Wong Wednesday 17 March 2021, 06:29:56 PM.

    It is now available at:

    Video recording of the live session will be available later tonight at Echo360 (under processing now).

  • Assignment 1 Q&A

    Posted by Raymond Wong Wednesday 17 March 2021, 03:13:00 PM.

    If there are any more questions regarding the spec, clarifications, or advice needed for a1, please attend the live session (in an hour), we will address them there. Otherwise, if there are too many questions in the WebCMS forums and cs3311 emails, your last-minute questions may not be responded to in time.

    As mentioned in the first lecture, if your question requires more interactions (e.g., require us to look at your system etc), the easiest way is to liaise with your tutor at the lab session.

  • Q11 of a1 and Quiz 3

    Posted by Raymond Wong Friday 12 March 2021, 06:00:31 PM.

    There are some questions regarding stored procedures in Q11. Please stick with the specification (i.e., 'create procedure'):

    create or replace procedure renew(pno integer) ...

    rather than 'create function'.

    JAS videos focus on functions, as we can easily map functions to procedures, by checking the PostgreSQL docs. They are in fact very similar. The main difference is that procedures do not have return values (similar to most procedural programming languages). One may argue that we can make a function that returns void, and that will make procedures almost the same as functions. However, since the way we call a function vs a procedure is different, you will need to follow the spec above to get through the auto-marking. The below example highlights this difference (you can try on grieg after loading preload.sql). If there are still questions, I will elaborate more at the next live session.

    Finally, although many of you are busy on a1, remember Quiz 3 is due tonight.

    CREATE FUNCTION change_brand() RETURNS void
    AS $$
      UPDATE insured_item SET brand = 'Holden' WHERE brand = 'Nissan' AND year < 2010;
    CREATE PROCEDURE unchange_brand()
    AS $$
      UPDATE insured_item SET brand = 'Nissan' WHERE brand = 'Holden' AND year < 2010;
    select * from insured_item;
    select change_brand();
    select * from insured_item;
    call unchange_brand();
    select * from insured_item;
    -- The following will result in error
    call change_brand();      
    select unchange_brand();

  • Live sessions tomorrow and next Wed

    Posted by Raymond Wong Tuesday 09 March 2021, 05:20:43 PM.

    JAS topic videos have covered each SQL topic very well.

    In the first half of the next 2 live sessions, I'm going to use the assignment 1 dataset as an example to further illustrate the concepts you learned from these topic videos (This week: SQL queries. Next week: functions & triggers). After that, we will continue as a Q&A help session, so bring your questions. See you tomorrow.

  • Reminder: Quiz 2 due tonight

    Posted by Raymond Wong Friday 05 March 2021, 04:13:20 PM.

    There are close to 100 students who haven't completed quiz 2 yet.

    Please remember there is a quiz due every Friday.

  • Assignment 1 Spec

    Posted by Raymond Wong Monday 01 March 2021, 01:15:13 PM.

    Assignment 1 spec is available. It is due on Friday 19th March 5:00pm AEST.

    Please read the spec carefully before you start.

    I'll go through the spec in detail (and answer any questions) during the live lecture this Wed 4-6pm.

    PS: remember to do the quizzes every week (except week 6).

  • Quiz 1 Released

    Posted by Dominic Wong Monday 22 February 2021, 09:13:31 AM.

    Quizzes will start from this week! Quiz 1 has been made available, and is due this Friday 11:59pm (26th Feb). You may access the quiz from ' Activities ', or under 'Upcoming Due Dates' on the home page.

    Multiple submissions are allowed, and only the final submission will be marked. Please don't leave it to the last minute, in order to avoid unnecessary troubles.

  • Live lecture recording available now

    Posted by Raymond Wong Monday 15 February 2021, 05:02:14 PM.

    The recording of today's live lecture is available now at Echo360 .

    Please note that the next live lecture will be on Wed 24/2 4-6pm (next week) via Collaborate.

  • Welcome

    Posted by Raymond Wong Monday 08 February 2021, 06:20:58 PM.

    Welcome to Database Systems.

    COMP3311 21T1 will still be fully online. Please read the Course Outline (just posted) for details.

    There are no labs nor tuts in Week 1.

    Labs start from Week 2, and Tuts start from Week 7. You can find the tentative schedule from the Course Outline.

    Lectures start from Week 1 (9am Feb 15) via Blackboard Collaborate. To join the lecture go to the Moodle site and click on the "Live lectures/tuts/labs" link. If you can't get up early, it will be recorded and made available afterward.

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