Please stock the hoodie
You use an online shop. The hoodie is sold out. You type: "Please stock the hoodie."
What happens to your message? It is saved. Later the shop counts how many people asked. If many people ask, the shop buys more hoodies. Then you can buy one.
That small story uses seven jobs. Every data system does them.
Key words
| Word | What it means | Example |
|---|---|---|
| Data system | A system that takes in data, keeps it and gives it back when needed. | An online shop |
| Input | Data going in to the system. | You type a request. |
| Search | Find the data you want. | Find every request for a hoodie. |
| Save | Keep the data so it is still there later. | The request is stored. |
| Integrate | Join data from different places. | Put a customer name beside a request. |
| Index | A list that points to where data is, so the system finds it fast. | The index at the back of a book |
| Output | Data coming out in a form people can use. | A list of the most asked items |
| Feedback loop | What comes out changes what goes in next time. | Stock the hoodie, and fewer people ask. |
| Database | An organised store of data. | The shop database |
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Quick check: guess the job
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Quick check: guess the job
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The seven jobs
A data system does seven jobs.
- Input: data goes in.
- Search: find data.
- Save: keep data.
- Integrate: join data from different places.
- Organise: use an index so finding is fast.
- Output: show or send data.
- Feedback loop: what comes out changes what goes in.
Try it: the seven jobs in code
requests = [] # Save: a list keeps the data
customers = {1: "Sam", 2: "Aisha"}
requests.append((1, "Hoodie")) # Input: data goes in
requests.append((2, "Hoodie"))
requests.append((1, "Cap"))
for request in requests: # Integrate: a name beside each request
print(customers[request[0]], "asked for", request[1])
hoodie = [] # Search: find the hoodie requests
for request in requests:
if request[1] == "Hoodie":
hoodie.append(request)
print("Hoodie requests:", len(hoodie))
requests.sort() # Organise: put the list in order
print(requests) # Output: show it
# Add one more request and run it again. See the output change.
The feedback loop
The output says the hoodie was asked for 2 times and the cap once. The shop decides to buy 20 hoodies. The decision changes the data: the stock goes up. When customers see it, fewer ask. The output has changed the input.