Course Notices | COMP9315 24T1

Assignment 2 Queries

Posted by John Shepherd Tuesday 07 May 2024, 09:27:25 PM, last modified Tuesday 07 May 2024, 09:28:33 PM.

I do not have time to reply to all the queries about assignment 2 auto-marking.

I am going to file them to be dealt with as soon as I have time.

Some general comments, though:

anyone with a preliminary mark of 0 will not end up with a final mark of 0
especially if this is due to the "create did not compile" problem
if you implemented MAH but the auto-marker thinks you didn't, this will be fixed
if you called getPage() too often and confused to page-call counter, we'll take it into account
etc etc etc etc

Be patient.

Assume that your assignment 2 mark will be reasonable and go into the exam with that in mind,

Exam Pointers

Posted by John Shepherd Tuesday 07 May 2024, 09:08:55 PM.

You login to the exam environment using your zID and zPass. If you don't know these, work them out before Thursday.

The exam environment is essentially VLab. If you're not familiar with VLab, get familiar by Thursday.

Bring your student card. If you don't have one, ... or bring photo ID (e.g. driver's licence, passport), but we'll want to know why you don't have a student card.

Apart from the exam paper, in the same format as the 22T1 paper, and templates for the answers, you'll have the Reference Sources and the Linux programmer's manual. You'll also have a sheet of paper on which to sign your name so we can check against the signature on your photo ID, and on which you can scribble. You can also bring a pen/pencil.

You cannot bring notes, calculators, watches, mobile phones, ear pods, headphones, laptops, tablets, etc. etc.

Assignment 2 Auto-marking

Posted by John Shepherd Tuesday 07 May 2024, 06:45:09 PM, last modified Tuesday 07 May 2024, 08:50:41 PM.

I've released a first cut of the assignment 2 auto marking.

A bunch of assignments slipped through with marks of 0.0 and error messages like:

Your code compiled successfully.
create did not compile
insert did not compile
select did not compile
stats did not compile

These need fixing, so you can ignore output like this. Annoyingly, there are about 80 of them. I will try to fix these before the exam.

Half a dozen didn't slip through and those people don't have marks yet.

People have pointed out other "issues" with the auto-marking. I will investigate these, but probably not before the exam. Marks can always be fixed later. I won't leave buggy auto-marks lingering in your transcript.

It didn't help that many people submitted an ass2.zip file with the actual file buried within a directory, sometimes two level deep.

Update : I've fixed all the "testing.out: No such file or directory" problems. Most of them already had marks in SMS. Some rolled over to the "create did not compile problem" above.

Exam Materials

Posted by John Shepherd Tuesday 30 April 2024, 02:41:38 PM.

People keep asking "What will I have access to in the exam?"

I've put together a page that shows all of the Reference Sources available in the exam.

The exam is a closed environment and this is all of the material you get.

You cannot bring your own notes. You cannot bring your own laptop.

Sample solutions to 22T1 exam

Posted by John Shepherd Wednesday 24 April 2024, 04:52:46 PM.

Sample solutions for the 22T1 Final Exam are now available.

Seating Allocations for Exam

Posted by John Shepherd Monday 22 April 2024, 07:23:07 PM, last modified Tuesday 23 April 2024, 09:33:43 AM.

By now, you have probably received an email pointing you at a website which holds the teaching allocations.

If not, go to: https://cgi.cse.unsw.edu.au/~exam/24T1/seating/register.cgi/allocations/

Update:

I seem to have been over-keen to get this information out. It looks like the seating allocations for COMP9315 are not yet ready. I'll ask the people who run the site when they are likely to be available.

Update #2:

The seating allocations should be available by the weekend. They are releasing them in the order that the exams run. Our exam is last :-(

Assignment 1 Marks

Posted by John Shepherd Thursday 18 April 2024, 06:26:58 PM, last modified Friday 19 April 2024, 03:23:56 PM.

I posted the remaining Assignment 1 marks today as PRELIMINARY results.

The assignments I posted today mostly did very poorly on the auto-marking.

I will check all of them to see whether the problem is the code or whether they have triggered some edge case in the auto-marking script.

You can see the full output from the auto-marking by going to the "Assignment 1 Submission" page and clicking on the "Collect Submission" tab. If it has the word PRELIMINARY at the bottom, then that's not your final mark.

If your mark is 0 (or close to 0) that is definitely not your final mark.

Reminder: Help Sessions

Posted by John Shepherd Monday 15 April 2024, 10:20:48 AM.

Help Sessions this week (April 15-19): Monday 10-12, Tuesday 3-4.

Ass2 Bug Fix

Posted by John Shepherd Tuesday 09 April 2024, 09:10:03 AM.

In the reln.c file in the addToRelation() function, the code to set the page number when d=0 is wrong.

Change

if (r->depth == 0) p = 1;

to

if (r->depth == 0) p = 0;

This only causes a problem if the initial file size is 1 page.

Help Sessions in Week 9

Posted by John Shepherd Monday 08 April 2024, 10:02:31 PM.

Tuesday 9-10.30, Thursday 10-12, Friday 11-1 all in K17-410

Assignment 2 (fix)

Posted by John Shepherd Monday 01 April 2024, 09:06:45 PM.

Shuhao and Franco pointed out a bug in the supplied code. In the function tupleHash() in tuple.c , it makes a buffer that is too small. A quick fix: change

char buf[MAXBITS+1];

to

char buf[MAXBITS+5];

Since you'll be modifying tupleHash() for the assignment, make sure you fix this.

I've updated ass2.zip to include this fix.

Assignment 2

Posted by John Shepherd Saturday 23 March 2024, 09:42:28 PM, last modified Saturday 30 March 2024, 03:57:28 PM.

The Assignment 2 Specifcation and starter code is now available. Testing instructions to follow, although you should be able to work out your own test cases pretty easily.

Update: You can now submit the assignment.

vxdb is Struggling again

Posted by John Shepherd Tuesday 19 March 2024, 03:58:08 PM.

You are currently (Tue 4pm) doing two things which are making vxdb's life difficult:

using the Remote-SSH plugin to VS Code, which is a resource hog ... use SSH-FS instead
details on SSH-FS at https://www.cse.unsw.edu.au/~<wbr>learn/homecomputing/sshfs

I thought your PostgreSQL servers were killed when you logged out, but some seem to linger on. Please stop your server when you finish your session with PostgreSQL ( p0 or pg_ctl stop ).

Note that control-Z does NOT quit your psql process or server. It leaves it suspended in the backgound, consuming resources for no good purpose. You can restart a suspended psql process using the fg command from the shell and then quit it properly with \q. After you've quit all your psql processes, you should be able to stop your server.

vxdb is OK

Posted by John Shepherd Monday 18 March 2024, 10:04:04 AM, last modified Monday 18 March 2024, 10:07:14 AM.

Despite no reboot, vxdb looks usable:

:vxdb: uptime
 ... 28 users,load average: 0.78, 1.08, 3.19
:vxdb: df -h /tmp
Filesystem.   Size Used Avail Use% Mounted on
/dev/nvme0n1p1 49G  35G   13G  74% /

I've reset the deadline to midnight on Tuesday (19 March), to allow for the 48 hours of lost time of Thursday and Friday last week.

Get to work and finish it off, if you haven't already. Assignment 2 is coming ...

vxdb performance over last 48 hours

Posted by John Shepherd Saturday 16 March 2024, 02:47:43 PM.

You have been hammering vxdb not just process-wise but also disk-space wise for the last two days.

Load averages over 20 have not been uncommon, making the use of ./run_test.py problematic; but more importantly, the /tmp file system has been constantly close to full. Since PostgreSQL uses /tmp for various purposes, it has made it difficult to get things done.

Consequently, I won't be enforcing late penalties until the system support staff can clean out /tmp . This generally means rebooting the machine, so it will be unavailable for a 10-minute period at some point, after which (a) the load average will be near 0 and (b) /tmp will have almost 0 space usage. Good.

Do not leave things too long, because COMP9311 have an upcoming project deadline and they also use vxdb.

It has been disappointing that some people have encountered the /tmp problem because they are only now getting around to installing their postgresql-15.6 server.

PostgreSQL Server Not Responding

Posted by John Shepherd Thursday 14 March 2024, 10:50:35 PM, last modified Thursday 14 March 2024, 10:50:56 PM.

So, you run ./run_test.py and start getting messages about "server not responding"?

This is happening because, in one of the early tests, your code crashed your PostgreSQL server. Unfortunately, run_test.py continues blindly on attempting to run later tests with a dead server. Not helpful.

Your best bet is to not use run_test.py and try to work out exactly which of the tests caused your server to crash, by running the tests manually. The first half hour of today's lecture talked about how to do this.

The Bad News

Posted by John Shepherd Thursday 14 March 2024, 07:02:10 PM.

I have meetings all day tomorrow, so won't be available to answer questions.

In any case, the same questions are starting to recur and are all answered in the FAQ .

If you have code that worked a few days ago and doesn't quite work when vxdb is under heavy load, don't worry. PostgreSQL doesn't like heavy loads and I won't be testing it when the load is heavy.

Assignment 1

Posted by John Shepherd Wednesday 13 March 2024, 06:37:16 PM.

Once again, vxdb is not happy, and I'm sure it won't get better over the next few days as the rest of you decide that it's time to start work on the assignment.

Vxdb was quite responsive at 10am this morning and might be a reasonable proposition between 8am and 10am (although now that I've said that, eveyone will jump on in that time period and ...)

I will demonstrate how to run tests outside run_test.py in the Thursday lecture. If you've already worked this out, you can skip the first 30 mins of the lecture.

I will also run a Help Session from 10-12 on Thursday (March 14) from 10-12. Now that you're asking me to debug memory errors it takes at least 10 mins per person, which means at most 12 will get help over the 2 hours.

As for extensions, some people were smart and started the assignment early, submitted two weeks ago, and have moved onto other courses. They will not be happy if I give an extension to help out all the people who didn't start earlier, as suggested. Learn the lesson for the next assignment. Start early. Avoid the deadline rush.

Load on vxdb

Posted by John Shepherd Tuesday 12 March 2024, 10:18:45 PM.

There is currently a very heavy load on vxdb . The run_test.py script takes a l-o-n-g time to start, and a long time to run each test.

You're probably better off testing manually by looking at what's in the tests directories and loading the schemas and data and running the tests using psql -f

This is a bad sign for the rest of the week.

Assignment FAQ

Posted by John Shepherd Sunday 10 March 2024, 03:51:04 PM.

The same questions were being asked over and over about the assignment on the forum, so I distilled them into an FAQ . If your favourite question is missing, let me know and I'll add it.

Forget about Titles

Posted by John Shepherd Saturday 09 March 2024, 10:26:00 AM.

For the last time, do not waste time trying to detect and reject titles. There are too many possible titles to make this feasible (think "Prof", "Rev", "Col", "Bishop", "Seargent", "Admiral", etc. etc. etc. etc.). Instead, simply follow the grammar, which would allow things like like "Dr" (and the words above) to be treated as valid names. If a string like "Dr" occurs in a context where a name would be correct, then simply treat it as a name.

Help Session ... Friday 8 March

Posted by John Shepherd Thursday 07 March 2024, 02:28:12 PM.

Help Session ... Friday 8 March ... 2.30 - 4.30 ... K17-410

Help Session ... Monday 4 March

Posted by John Shepherd Sunday 03 March 2024, 09:46:26 PM.

Help Session ... Monday 4 March ... 10-12 ... K17-410

Give submission bug

Posted by John Shepherd Sunday 03 March 2024, 04:43:28 PM, last modified Sunday 03 March 2024, 04:43:49 PM.

If you submitted your Assignment 1 before March 2, you might want to submit it again.

It would gave given a message that had a date of 2022. I've fixed this to now be 2024.

Help Session Tue 27 Feb 3-5

Posted by John Shepherd Tuesday 27 February 2024, 11:26:09 AM.

I'll be in K17-410 from 3-5 on Tuesday 27 February to help with (a) PostgreSQL installation problems, (b) explaining the Assignment spec, (c) attempting to debug your Assignment code, in that order of priority.

Assignment 1 Testing Expected Outputs

Posted by John Shepherd Sunday 25 February 2024, 11:39:51 AM, last modified Sunday 03 March 2024, 02:44:46 PM.

Since nobody has complained about tests being flagged as FAIL after the removal of SET from the expected test outputs, I assume that this is no longer a problem.

Assignment 1 Testing Notes

Posted by John Shepherd Friday 23 February 2024, 01:54:21 PM.

Some notes on how to test your PersonName data type are now available.

Meeting after meeting after ...

Posted by John Shepherd Tuesday 20 February 2024, 12:12:11 PM.

I've been summoned to a meeting at 1.30, so I won't be doing the Help Session for around 30-40 mins starting then.

Quiz 1 Bug

Posted by John Shepherd Monday 19 February 2024, 06:53:03 PM.

If you did the quiz before 7pm on Monday 19 Feb, please do it again.

Some of the "answers" were buggy and many people scored zero.

Lucky you! Quiz extra time

Posted by John Shepherd Monday 19 February 2024, 06:40:36 PM.

They're not shutting down the CSE servers until 8pm on Friday.

But I wouldn't leave it until then to submit the quiz. Before 7.30 would be safer.

New Stuff

Posted by John Shepherd Monday 19 February 2024, 03:02:02 PM.

Some new things on the web site today:

Week 02 Preview video
Assignment 1 specification
Quiz #1
Moodle , which now has both Monday and Thursday lecture links

Echo360 Recordings

Posted by John Shepherd Sunday 18 February 2024, 12:13:51 PM.

Hmmm ... we now have the "unusual" scenario where there are two links in Moodle to the Echo360 lecture recordings: one for Monday Lectures, one for the Thursday Lectures. Thank you UNSW.

Help Session on Tuesday

Posted by John Shepherd Sunday 18 February 2024, 11:46:02 AM, last modified Sunday 18 February 2024, 11:46:33 AM.

It seems I need to run another Help Session for people to get their PostgreSQL servers installed.

I can't do it on Monday (thanks to meetings, and, of course, a lecture), but can do Tuesday 11.30 - 3.00.

Just come to my office K17-410and show me what you tried and what the outcome was.

If you get the problem with locale, try the command : initdb --no-locale --encoding=UTF8

I'll add this suggestion (thanks to Hao Wang) to P01.

Video of Thursday Lecture

Posted by John Shepherd Friday 16 February 2024, 09:06:11 AM, last modified Friday 16 February 2024, 09:07:57 AM.

The Echo360 video of Thursday's lecture doesn't seem to have appeared on the Echo360 site. I'll ask about that this morning.

My video of the lecture is sitting on my laptop at work. I'm stuck at home until midday. I'll upload it to YouTube as soon as I get to work.

If the Echo360 video is irretrievably lost, I'll replace it on Echo with my video. So, either way, there will be a video on YouTube and a video on Echo360.

Help Session Today (Wed 14 Feb)

Posted by John Shepherd Wednesday 14 February 2024, 08:28:24 AM.

Valentine's Day Help Session in K17-410 from 1pm-3pm, primarily to look at PostgreSQL installation issues. Bring heart-shaped chocolates.

New stuff on website

Posted by John Shepherd Tuesday 13 February 2024, 12:00:20 PM.

I've fixed the slides from the Monday lecture and upload my video of that lecturen onto YouTube.

I've also opened all the Prac Exercises. I've only checked Prac 01. I'll check the other exercises tomorrow, but let me know if they mention anything weird like grieg or srvr or pgs .

Number of Quizzes

Posted by John Shepherd Monday 12 February 2024, 10:01:04 PM.

In the lecture today, I said there were 6 quizzes. The schedule in the course outline only has 5. There are only 5. I will fix the lecture slides, but fixing the lecture *video* is beyond my video editing capabilities.

Moodle Website

Posted by John Shepherd Sunday 11 February 2024, 09:56:01 PM, last modified Monday 12 February 2024, 06:42:50 AM.

Aha! I found the Moodle website for this course.

For some unknown reason (and not fixable by me), it has the title

COMP9315 Database Systems Implementation 2021 T1

The URL is https://moodle.telt.unsw.edu.au/course/view.php?id=81678

Update: there may be more problems than just the title. I will need to ask the people who run Moodle to fix the Moodle site. But, really, the Moodle site is a sideshow. The main site is this Webcms3 one.

Welcome and Polls

Posted by John Shepherd Saturday 10 February 2024, 03:30:08 PM.

Now that I've fixed the Webcms3 enrolment uploads, all enrolled students should receive this message.

There are some polls for you to take; there's a Course Outline to read.

And I'll start posting content on the website tomorrow (Sunday), including an intro video.

See you in the lecture on Monday at 4pm in Ainsworth G03.

COMP9315 Lectures

Posted by John Shepherd Sunday 07 January 2024, 03:56:04 PM, last modified Tuesday 09 January 2024, 01:29:00 PM.

There are two 2-hour lectures each week for this course, both in Ainsworth G03.

Monday 4pm - 6pm, Thursday 4pm - 6pm

UNSW Timetabling has a strange presentation of the classes for many courses, so strange that I removed the "Timetable" link from the Webcms3 site.

The view of the Timetable that I have seems to have multiple PG and UG concurrent lectures and multiple "Online" streams. The lectures will be as above, will be recorded, at least by me if not by Echo360, but will *not* be live-streamed.

Important notes for COMP9315

Posted by John Shepherd Sunday 07 January 2024, 01:08:57 PM.

COMP9315 is a course on the internals of classical relational database management systems.

It assumes that you know about relational databases from the user side (e.g. COMP9311 or COMP3311), but much more importantly, it assumes that you have a sound knowledge of data structures for searching such as trees and hash tables (e.g. COMP9024 or COMP2521) and are a very confident and competent C programmer. Both assignments require you to write C code, and the exam requires you to write C code.

Note that this course cannot be taken remotely. In particular you are required to attend the exam in person in the CSE labs where your work will be monitored (invigilated), in a closed environment (i.e. no internet access).

If the above does not appeal to you, don't take this course.

COMP9315 Notices

Notices