PyData Sofia May 2024 - Intro to Apache Arrow

Exploring the text that powers the modern data (science) stack

1. Apache Arrow

Exploring the tech that powers the
modern data (science) stack
Uwe Korn – QuantCo – May 2024

2. About me
•Uwe Korn

https://mastodon.social/@xhochy / @xhochy

https://www.linkedin.com/in/uwekorn/
•CTO at Data Science startup QuantCo
•Previously worked as a Data Engineer
•A lot of OSS, notably Apache {Arrow,
Parquet} and conda-forge
•PyData Südwest Co-Organizer

3. Agenda
1.Why do we need this?
2.What is it?
3.What’s its impact?

4. Why do we need this?
•Different Ecosystems
•PyData / R space
•Java/Scala „Big Data“
•SQL Databases
•Different technologies
•Pandas / SQLite

5. Why solve it?
•We build pipelines to move data
•We want to use all tools we can leverage
•Avoid working on converters or waiting for the data to be converted

8. Introducing Apache Arrow
•Columnar representation of data in main memory
•Provide libraries to access the data structures
•Building blocks for various ecosystems to use them
•Implements adopters for existing structures

9. Columnar?

10. All the languages!
1.„Pure“ implementations in

C++, Java, Go, JavaScript, C#, Rust, Julia, Swift, C(nanoarrow)
2.Wrappers on-top of them in

Python, R, Ruby, C/GLib, Matlab

11. There is a social component
1.A standard is only as good as its usage
2.Different communities came together to form Arrow
3.Nowadays even more use it to connect

12. Arrow Basics
1.Array: a sequence of values of the same type in contiguous buffers
2.ChunkedArray: a sequence of arrays of the same type
3.Table: a sorted dictionary of ChunkedArrays of the same length

13. Arrow Basics: valid masks
1.Track null_count per Array
2.Each array has a buffer of bits indicating whether a value is valid,

i.e. non-null

14. Arrow Basics: int array
Python array: [1, null, 2, 4, 8]
Length: 5, Null count: 1
Validity bitmap buffer:
| Byte 0 (validity bitmap) | Bytes 1-63 |
|--------------------------|-----------------------|
| 00011101 | 0 (padding) |
Value Buffer:
| Bytes 0-3 | Bytes 4-7 | Bytes 8-11 | Bytes 12-15 | Bytes 16-19 | Bytes 20-63 |
|-------------|-------------|-------------|-------------|-------------|-----------------------|
| 1 | unspecified | 2 | 4 | 8 | unspecified (padding) |

15. Arrow Basics: string array
Python array: ['joe', null, null, 'mark']
Length: 4, Null count: 2
Validity bitmap buffer:
| Byte 0 (validity bitmap) | Bytes 1-63 |
|--------------------------|-----------------------|
| 00001001 | 0 (padding) |
Offsets buffer:
| Bytes 0-19 | Bytes 20-63 |
|----------------|-----------------------|
| 0, 3, 3, 3, 7 | unspecified (padding) |
Value buffer:
| Bytes 0-6 | Bytes 7-63 |
|----------------|-----------------------|
| joemark | unspecified (padding) |

16. Impact!
Arrow is now used in all „edges“ where data passes through:
•Databases, either in clients or in UDFs
•Data Engineering tooling
•Machine Learning libraries
•Dashboarding and BI applications

17. Examples of Arrow’s
massive Impact
If it ain’t a 10x-100x+ speedup, it ain’t worth it.

18. Parquet

19. Anatomy of a Parquet file

20. Parquet
1.This was the first exposure of Arrow to the Python world
2.End-users only see pandas.read_parquet
3.Actually, it is:
A.C++ Parquet->Arrow reader
B.C++ Pandas<->Arrow Adapter
C.Small Python shim to connect both and give a nice API

22. DuckDB Interop
1.Load data in Arrow
2.Process in DuckDB
3.Convert back to Arrow
4.Hand over to another tool
All the above happened without any serialization overhead

23. DuckDB Interop

24. Fast Database Access

25. Fast Database Access
Nowadays, you get even more speed with
•ADBC – Arrow DataBase Connector
•arrow-odbc

26. Should you use Arrow?
1.Actually, No.
2.Not directly, but make sure it is used in the backend.
3.If you need performance, but the current exchange is slow; then dive
deeper.
4.If you want to write high-performance, framework-agnostic code.

27. The ecosystem
…and many more.…

https://arrow.apache.org/powered_by/

28. Questions?
Follow me:

https://mastodon.social/@xhochy / @xhochy

https://www.linkedin.com/in/uwekorn/