This presentation explains how I use Neo4J as a database for a tool that calculate spreadsheet metrics.

1. Spreadsheets are graphs too!
Felienne Hermans (@felienne)

2. Spreadsheets are graphs too!
Felienne Hermans (@felienne)
In this slidedeck I explain how I
used Neo4J to store information on
spreadsheets

3. Ehm...spreadsheets?
They are so tably?
Are you sure they are fit for a graph
database?

4. Spreadsheets are mislabeled

5. Spreadsheets are mislabeled
People often think of spreadsheets
as data, but...

6. Spreadsheets are code

7. Spreadsheets are code
I have made it my life’s work to
spread the happy word
“Spreadsheets are code!”

8. Spreadsheets are code
I have made it my life’s work to
spread the happy word
“Spreadsheets are code!”
If you don’t immediately believe
me, I have three reasons*
* If you do believe me, skip the next 10 slides ;)

9. 1) Used for similar problems

10. This tool (for stock price
computation) could have been
built in any language. C,
JavaScript, COBOL, or Excel.
The problems Excel is used for are
often (not always) similar to
problems solved in different
languages.

11. 2) Formulas are Turing complete

12. 2) Formulas are Turing complete
I go to great lengths to make my
point. To such great lengths that I
built a Turing machine in Excel,
using formulas only.

13. Here you see it in action. Every row
is an consecutive step of the lint.
This makes it, in addition to a proof
that formulas are Turing complete,
Also a nice visualization of a Turing
machine.

14. 3) They suffer from the same problems

15. 3) They suffer from the same problems

16. 3) They suffer from the same problems

17. 3) They suffer from the same problems

18. In summary: both the activities,
complexity and problems are the same

19. So if spreadsheets are code, can we
apply software engineering methods?

21. In my dissertation, I defined smells
for spreadsheet formulas

22. Turns out, Fowler’s code smells are easily
transferable to spreadsheets

23. Pop quiz: what smell is this?

24. It is the ‘feature envy’ smell

25. See how easily this applies to
spreadsheets

26. To analyze smells, we save spreadsheet
info to a database

27. This is the data model that I am
storing to the database.
The basics are pretty simple.

28. This is the data model that I am
storing to the database.
The basics are pretty simple.
But cells can refer to each other,
either directly (i.e. =A7+A9)
=A7+A9

29. =A7+A9=SUM(A1:A5)
This is the data model that I am
storing to the database.
The basics are pretty simple.
But cells can refer to each other,
either directly [=A7+A9] or through
a range [=SUM(A1:A5)]

30. This is the data model that I am
storing to the database.
The basics are pretty simple.
But cells can refer to each other,
either directly [=A7+A9] or through
a range [=SUM(A1:A5)]
In the case of a range, the range
itself will points to the cells it
contains.
=SUM(A1:A5) A1..A5

31. You know the saying that if all you
have is a hammer, everything is a
nail to you.
This is what happened to me. I did
not think about what type of
database to use.

32. SQL
You know the saying that if all you
have is a hammer, everything is a
nail to you.
This is what happened to me. I did
not think about what type of
database to use.
I just started banging with the
good ol’ SQL hammer I had been
using for ever.

33. Number of worksheets in a spreadsheet
Which started out just fine!

34. Number of cells in a spreadsheet
Still pretty okay

35. Number of connected cells for a cell
But, in order to calculate the
‘feature envy’ smell, we need the
total number of connected cells.
So both direct and through a
range.

36. Number of connected cells for a cell
But, in order to calculate the
‘feature envy’ smell, we need the
total number of connected cells.
So both direct and through a
range.
Let’s start with direct.

37. Number of connected cells for a cell

38. Number of connected cells for a cell
But, in order to calculate the
‘feature envy’ smell, we need the
total number of connected cells.
So both direct and through a
range.
Let’s start with direct.
Now look at the range part.

39. Number of connected cells for a cell

40. Number of connected cells for a cell

41. Number of connected cells for a cell
Things start to get iffy when we
combine these two query parts.

42. Number of connected cells for a cell

43. Number of connected cells for a cell
Things start to get iffy when we
combine these two query parts.
Not only is the query quite big, also
this happens.

44. Number of connected cells for a cell

45. If your tools reach their limits, this
has to tell you something.
So I started thinking.

46. Maybe this
is not a
nail…

48. Maybe I
need a
different tool

49. Maybe I
need a
different tool
It was at this time that I attended a
talk about Neo4J.
And the strange thing is, I had
seen a few talks about Neo before.
But this time it ‘clicked’, because I
was suffering from the problem
that Neo could solve.

50. So I ended up with this
model. Still spreadsheets,
worksheets, cells and links.

51. So I ended up with this
model. Still spreadsheets,
worksheets, cells and links.
But the ‘prec’ relation can
now refer to either cells or
ranges.

52. Turning this

53. Turning this into this.

54. Turning this into this.
I wouldn’t say this is the power of
Neo at work. It is the power of the
right tool for the job.
There are scenarios, for sure,
where the situation is the other
way around.
But for my goal, Neo was a great
fit.

55. Also, to be honest with you, I did
not immediately write such super
succint Cypher queries. My first
attempt was something like this:

56. Also, to be honest with you, I did
not immediately write such super
succint Cypher queries.
My first attempt was something like
this

57. Also, to be honest with you, I did
not immediately write such super
succint Cypher queries.
My first attempt was something like
this
This is basically a one on one
translation from SQL to Neo. Still the
two different ways of connecting. It
took me a while to understand the
power of traversal queries.
Here’s another example:

58. Number of cells in a spreadsheet

59. Number of cells in a spreadsheet
First Cypher attempt
Still very SQLy

60. Number of cells in a spreadsheet
Second (okay probably more like
fifth) attempt. No more where,
directly matching a graph pattern.
The power of Cypher :)

61. That’s all folks.
Spreadsheets are code

62. That’s all folks.
Spreadsheets are code
Don’t justhit things with the one
hammer you know

63. That’s all folks.
Spreadsheets are code
Don’t justhit things with the one
hammer you know
Neo is cool for graph like structures

64. That’s all folks.
Spreadsheets are code
Don’t justhit things with the one
hammer you know
Neo is cool for graph like structures
It makes queries easier

65. That’s all folks.
Spreadsheets are code
Don’t justhit things with the one
hammer you know
Neo is cool for graph like structures
It makes queries easier
But it takes some getting used to
for SQL minded brains

66. Spreadsheets are graphs too!
Felienne Hermans (@felienne)
That’s all folks.
Spreadsheets are code
Don’t justhit things with the one
hammer you know
Neo is cool for graph like structures
It makes queries easier
But it takes some getting used to for
SQL minded brains
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