[BEAM-10937] Tour of Beam: Reading and writing data notebook

[davidcavazos]

This is the second introductory notebook on how to read and write data.

It covers:

• Basic I/O concepts
• ReadFromText and WriteToText transforms
• Creating new sources
  • Creating data from generators
  • Reading data from SQLite
• Creating new sinks
  • Writing fixed-sized batches
  • Writing windows of elements

R: @aaltay
R: @rosetn

Staged:

• New notebook: https://colab.research.google.com/github/davidcavazos/beam/blob/tour-of-beam-reading-writing-data/examples/notebooks/tour-of-beam/reading-and-writing-data.ipynb
• Updated "What's next" section: https://colab.research.google.com/github/davidcavazos/beam/blob/tour-of-beam-reading-writing-data/examples/notebooks/tour-of-beam/getting-started.ipynb
• Added new entry: http://apache-beam-website-pull-requests.storage.googleapis.com/14045/get-started/tour-of-beam/index.html

Note: I tried reading from public Cloud Storage data and public BigQuery data, but they all required authentication, so I decided to not include them.

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Post-Commit Tests Status (on master branch)

Lang	SDK	Dataflow	Flink	Samza	Spark	Twister2
Go		---		---		---
Java
Python				---		---
XLang				---		---

Pre-Commit Tests Status (on master branch)

---	Java	Python	Go	Website	Whitespace	Typescript
Non-portable
Portable	---		---	---	---	---

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GitHub Actions Tests Status (on master branch)

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[davidcavazos]

Will need to be added to the landing page #13747 as well, whichever merges first.

[aaltay]

I glanced at this. It looks good. Some high level comments:

• I am not sure the info boxes related to disk speeds are relevant. Read/Write might be mostly happening to a service and very unlikely to use in memory sources.
• The parts that refer to creating a sink transform and creating a source transform might cause confusion. Especially the source one, since source has a specific meaning.

I would like to load balance these reviews across the team. For this one I will nominate @emilymye in addition to @rosetn.

Feel free to ping me once this is ready to merge after both reviews.

[davidcavazos]

Got it, I removed the info boxes about the disk speeds. I'm also renaming "Source" to "input transform" and "Sink" to "output transform" since that might be more accurate terms.

[emilymye]

Will defer to @rosetn for rest of review :)

[davidcavazos]

Thanks for the comments, here's the updated version.

[davidcavazos]

Hi @emilymye, can you take a look at this whenever you have a chance? Thank you!

[davidcavazos]

Hi @rosetn, I've addressed your review comments, please let me know what you think.

[rosetn]

Look great, David!

[davidcavazos]

Friendly ping @emilymye :)

[emilymye]

LGTM! @aaltay will have to actually approve and submit because I don't have committer access.

[aaltay]

Thank you! And thank you for the reviews!