Effectieve query-uitvoering

Data-pipelines schalen en optimaliseren met Polars

Liam Brannigan

Data Scientist & Polars Contributor

Maak kennis met je instructeur

Liam Brannigan, Lead Data Scientist
ML- en data-engineeringspecialist
Polars-bijdrager

Foto van Liam Brannigan - de instructeur van deze course

Van laptop naar cloud

Polars-pipeline schaalt van laptop naar cloud

Is deze course iets voor jou?

Polars-cursuspagina's

Een luie query maken met scan_csv
Expressies schrijven met filter, select en group_by

Hoofdstuk 1 - optimalisatie

Queryoptimalisatie

Hoofdstuk 1 - optimalisatie

Queryoptimalisatie

Hoofdstuk 2 - efficiënte I/O

Afbeelding van Polars die meerdere bestandstypen inleest

Hoofdstuk 3 - rijkere dtypes

Diagram van geneste data getransformeerd naar een tabel.

Hoofdstuk 4 - pipelines opschalen

Afbeelding van een grote tabel die wordt gestreamd.

Chicago-requests dataset

Het data-analyticateam van de burgemeester van Chicago

De dataset inspecteren

requests = pl.scan_csv("311_Service_Requests.csv",try_parse_dates=True)

Een enorme dataset met alle serviceverzoeken van Chicago-inwoners

De dataset inspecteren

requests.collect()

De dataset inspecteren

requests.collect().head(5)

shape: (5, 39)
| TYPE                          | STATUS    | DEPARTMENT     | CREATED_DATE        | ... |
| ---                           | ---       | ---            | ---                 | --- |
| str                           | str       | str            | str                 | ... |
|-------------------------------|-----------|----------------|---------------------|-----|
| Pothole in Street Complaint   | Completed | Transportation | 2019-12-16T10:09:08 | ... |
| Tree Trim Request             | Cancelled | Sanitation     | 2019-09-18T01:05:08 | ... |
| Garbage Cart Maintenance      | Completed | Sanitation     | 2021-01-24T09:14:58 | ... |
| Pothole in Street Complaint   | Completed | Transportation | 2019-03-21T10:41:01 | ... |
| Recycling Pick Up             | Completed | Sanitation     | 2021-02-16T08:28:59 | ... |

Verwerkte rijen beperken

requests.head(5)

Verwerkte rijen beperken

requests.head(5).collect()

shape: (5, 39)
| TYPE                            | STATUS    | DEPARTMENT     | CREATED_DATE        | ... |
| ---                             | ---       | ---            | ---                 | --- |
| str                             | str       | str            | str                 | ... |
|---------------------------------|-----------|----------------|---------------------|-----|
| Pothole in Street Complaint     | Completed | Transportation | 2019-12-16T10:09:08 | ... |
| Tree Trim Request | Completed | Sanitation     | 2019-09-18T01:05:08 | ... |
| Garbage Cart Maintenance        | Completed | Sanitation     | 2021-01-24T09:14:58 | ... |
| Pothole in Street Complaint     | Completed | Transportation | 2019-03-21T10:41:01 | ... |
| Recycling Pick Up               | Completed | Sanitation     | 2021-02-16T08:28:59 | ... |

Stel collect uit

Query: samenvatting per afdeling

completed_by_department

Query: samenvatting per afdeling

completed_by_department = requests

Query: samenvatting per afdeling

completed_by_department = requests.filter(
    pl.col("STATUS") == "Completed"
)

Query: samenvatting per afdeling

completed_by_department = requests.filter(
    pl.col("STATUS") == "Completed"
).collect()

Query: samenvatting per afdeling

completed_by_department = requests.filter(
    pl.col("STATUS") == "Completed"
).collect().group_by("DEPARTMENT").len()

Query: samenvatting per afdeling

completed_by_department = requests.filter(
    pl.col("STATUS") == "Completed"
).group_by("DEPARTMENT").len().collect()

shape: (10, 2)
| DEPARTMENT                     | len     |
| ---                            | ---     |
| str                            | u32     |
|-------------------------------|---------|
| 311 City Services              | 4859161 |
| Sanitation                     | 3406631 |
| Aviation                       | 2337842 |
| CDOT - Department of Transport | 1468240 |

Uitelopende querytakken

completed_by_department = requests.filter(
    pl.col("STATUS") == "Completed"
).group_by("DEPARTMENT").len()

completed_by_month = requests.filter(
    pl.col("STATUS") == "Completed"
).group_by("MONTH").len()

Hoe het team dit nu draait

completed_by_department.collect()
completed_by_month.collect()

Uitelopende queries uitvoeren

results = pl.collect_all(


)

Uitelopende queries uitvoeren

results = pl.collect_all([
    completed_by_department,
    completed_by_month,
])

Uitelopende queries uitvoeren

results[0]  # completed_by_department
shape: (10, 2)
| DEPARTMENT           | len     |
| ---                  | ---     |
| str                  | u32     |
|----------------------|---------|
| 311 City Services    | 4859161 |
| Sanitation           | 3406631 |
| Aviation             | 2337842 |
| Transport            | 1468240 |

results[1]  # completed_by_month
shape: (12, 2)
| MONTH | len  |
| ---   | ---  |
| i64   | u32  |
|-------|------|
| 1     | 2506 |
| 2     | 4566 |
| 3     | 2739 |
| 4     | 2922 |

Laten we oefenen!

Data-pipelines schalen en optimaliseren met Polars