course-info

GitHub Repo for http://db.csail.mit.edu/6.830/

We will be using git, a source code control tool, for labs in 6.830. This will allow you to download the code for the labs, and also submit the labs in a standardized format that will streamline grading.

You will also be able to use git to commit your progress on the labs as you go.

Course git repositories will be hosted as a repository in GitHub. GitHub is a website that hosts runs git servers for thousands of open source projects. In our case, your code will be in a private repository that is visible only to you and course staff.

This document describes what you need to do to get started with git, and also download and upload 6.830/6.814 labs via GitHub.

Contents

• Learning Git
• Setting up GitHub
• Installing Git
• Setting up Git
• Getting Newly Released Labs
• Submitting Your Labs
• Word of Caution
• Help!

Learning Git

There are numerous guides on using Git that are available. They range from being interactive to just text-based. Find one that works and experiment; making mistakes and fixing them is a great way to learn. Here is a link to resources that GitHub suggests: https://help.github.com/articles/what-are-other-good-resources-for-learning-git-and-github.

If you have no experience with git, you may find the following web-based tutorial helpful: Try Git.

Setting Up GitHub

Now that you have a basic understanding of Git, it's time to get started with GitHub.

0. Install git. (See below for suggestions).

1. If you don't already have an account, sign up for one here: https://github.com/join.

2. Make sure you are part of the GitHub Organization that we've created for the course: MIT-DB-Class. You should have received an invitation to join via email.

   You should now have a repository set up just for your lab solutions. This should be called homework-solns-2016-<athena username> and located in the MIT-DB-Class organization.

   This is what you'll set up in the next section to allow you to write your lab answers and submit them.

Installing git

The instructions are tested on bash/linux environments. Installing git should be a simple apt-get / yum / etc install.

Instructions for installing git on Linux, OSX, or Windows can be found at GitBook: Installing.

If you are using Eclipse, many versions come with git configured. The instructions will be slightly different than the command line instructions listed but will work for any OS. Detailed instructions can be found at EGit User Guide or EGit Tutorial.

Setting Up Git

You should have Git installed and have joined the MIT-DB-Class organization from the previous section.

1. The first thing we have to do is to clone the current lab repository by issuing the following commands on the command line:

    $ git clone git@github.com:MIT-DB-Class/simple-db-hw.git

   This will make a complete replica of the lab repository locally. Now we are going to change it to point to your personal repository that was created for you in the previous section.

   If you get an error that looks like:

    Cloning into 'lab'...
    Permission denied (publickey).
    fatal: Could not read from remote repository.

   Most likely the cause is that you just haven't finished setting up your GitHub account. You just need to setup an SSH key to allow pushing and pulling over SSH.

   Change your working path to your newly cloned repository:

    $ cd simple-db-hw/

2. By default the remote called origin is set to the location that you cloned the repository from. You should see the following:

    $ git remote -v
        origin git@github.com:MIT-DB-Class/simple-db-hw.git (fetch)
        origin git@github.com:MIT-DB-Class/simple-db-hw.git (push)

   We don't want that remote to be the origin. Instead, we want to change it to point to your repository. To do that, issue the following command:

    $ git remote rename origin upstream

   And now you should see the following:

    $ git remote -v
        upstream git@github.com:MIT-DB-Class/simple-db-hw.git (fetch)
        upstream git@github.com:MIT-DB-Class/simple-db-hw.git (push)

3. Lastly we need to give your repository a new origin since it is lacking one. Issue the following command, substituting your athena username:

    $ git remote add origin git@github.com:MIT-DB-Class/homework-solns-2016-<athena-username>.git

   If you have an error that looks like the following:

Could not rename config section 'remote.[old name]' to 'remote.[new name]'

Or this error:

fatal: remote origin already exists.

This appears to happen to some depending on the version of Git they are using. To fix it, just issue the following command:

```bash
$ git remote set-url origin git@github.com:MIT-DB-Class/homework-solns-2016-<athena username>.git

This solution was found from StackOverflow thanks to Cassidy Williams.

For reference, your final git remote -v should look like following when it's setup correctly:

 $ git remote -v
     upstream git@github.com:MIT-DB-Class/simple-db-hw.git (fetch)
     upstream git@github.com:MIT-DB-Class/simple-db-hw.git (push)
     origin git@github.com:MIT-DB-Class/homework-solns-2016-<athena username>.git (fetch)
     origin git@github.com:MIT-DB-Class/homework-solns-2016-<athena username>.git (push)

4. Let's test it out by doing a push of your master branch to GitHub by issuing the following:

    $ git push -u origin master

   You should see something like the following:

    Counting objects: 59, done.
    Delta compression using up to 4 threads.
    Compressing objects: 100% (53/53), done.
    Writing objects: 100% (59/59), 420.46 KiB | 0 bytes/s, done.
    Total 59 (delta 2), reused 59 (delta 2)
    remote: Resolving deltas: 100% (2/2), done.
    To git@github.com:MIT-DB-Class/homework-solns-2016-<athena username>.git
     * [new branch]      master -> master
    Branch master set up to track remote branch master from origin.
   

5. That last command was a bit special and only needs to be run the first time to setup the remote tracking branches. Now we should be able to just run git push without the arguments. Try it and you should get the following:

    $ git push
      Everything up-to-date

If you don't know Git that well, this probably seemed very arcane. Just keep using Git and you'll understand more and more. You aren't required to use commands like commit and push as you develop your labs, but will find them useful for debugging. We'll provide explicit instructions on how to use these commands to actually upload your final lab solution.

Getting Newly Released Labs

(You don't need to follow these instructions until Lab 2.)

Pulling in labs that are released or previous lab solutions should be easy as long as you set up your repository based on the instructions in the last section.

1. All new lab and previous lab solutions will be posted to the labs repository in the class organization.

   Check it periodically as well as Piazza's announcements for updates on when the new labs are released.

2. Once a lab is released, pull in the changes from your simpledb directory:

    $ git pull upstream master

   OR if you wish to be more explicit, you can fetch first and then merge:

    $ git fetch upstream
    $ git merge upstream/master

   Now commit to your master branch:

    $ git push origin master

3. If you've followed the instructions in each lab, you should have no merge conflicts and everything should be peachy.

Submitting Your Labs

You may submit your code multiple times; we will use the latest version you submit that arrives before the deadline (before 11:59 PM on the due date). Place the write-up in a file called lab#-writeup.txt, which has been created for you in the top level of your simple-db-hw directory.

You need to explicitly add any other files you create, such as new *.java files.

The criteria for your lab being submitted on time is that your code must be tagged and pushed by the date and time. This means that if one of the TAs or the instructor were to open up GitHub, they would be able to see your solutions on the GitHub web page.

Just because your code has been committed on your local machine does not mean that it has been submitted; it needs to be on GitHub.

There is a bash script turnInLab1.sh in the root level directory of simple-db-hw that commits your changes, deletes any prior tag for the current lab, tags the current commit, and pushes the tag to github. If you are using Linux or Mac OSX, you should be able to run the following:

$ ./turnInLab1.sh

You should see something like the following output:

$ ./turnInLab1.sh 
error: tag 'lab1submit' not found.
remote: warning: Deleting a non-existent ref.
To git@github.com:MIT-DB-Class/homework-solns-2016-<athena username>.git
- [deleted]         lab1submit
[master 7a26701] Lab 1
1 file changed, 0 insertions(+), 0 deletions(-)
create mode 100644 aaa
Counting objects: 3, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 353 bytes | 0 bytes/s, done.
Total 3 (delta 1), reused 0 (delta 0)
remote: Resolving deltas: 100% (1/1), completed with 1 local objects.
To git@github.com:MIT-DB-Class/homework-solns-2016-<athena username>.git
  069856c..7a26701  master -> master
* [new tag]         lab1submit -> lab1submit

If the above command worked for you, you can skip to item 6 below. If not, submit your solutions for lab 1 as follows (replace lab 1 with the correct lab ID for later labs):

1. Look at your current repository status.

   $ git status

2. Add and commit your code changes (if they aren't already added and commited).

    $ git commit -a -m 'Lab 1'

3. Delete any prior local and remote tag (this will return an error if you have not tagged previously; this allows you to submit multiple times)

   $ git tag -d lab1submit
   $ git push origin :refs/tags/lab1submit

4. Tag your last commit as the lab to be graded (again, update the lab ID for later labs)

   $ git tag -a lab1submit -m 'submit lab 1'

5. This is the most important part: push your solutions to GitHub.

   $ git push origin master --tags

6. The last thing that we strongly recommend you do is to go to the [MIT-DB-Class] organization page on GitHub to make sure that we can see your solutions.

Just navigate to your repository and check that your latest commits are on GitHub. You should also be able to check https://github.com/MIT-DB-Class/homework-solns-2016-<athena username>/tree/lab1

Word of Caution

Git is a distributed version control system. This means everything operates offline until you run git pull or git push. This is a great feature.

The bad thing is that you may forget to git push your changes. This is why we strongly suggest that you check GitHub to be sure that what you want us to see matches up with what you expect.

Help!

If at any point you need help with setting all this up, feel free to reach out to one of the TAs or the instructor. Their contact information can be found on the course homepage.

This page and infrastructure for this page was taken from https://github.com/MIT-DB-Class/course-info/blob/master/guides/course-setup.md and https://github.com/jdavis/github-plus-university