Sinking a cleaned extract to Parquet
Back to the Seattle library data. The team has a cleaned-up checkout extract they want to write to Parquet for downstream tools, but they don't want to materialize the whole thing in memory first. Write the lazy query straight to disk.
clean_checkouts is preloaded, along with the export path CLEAN_EXPORT_PATH.
Este ejercicio forma parte del curso
Scaling and Optimizing Data Pipelines with Polars
Instrucciones del ejercicio
- Write
clean_checkoutstoCLEAN_EXPORT_PATHdirectly from the lazy query. - Set the row group size to 5,000.
- Use the streaming engine.
ejercicio interactivo práctico
Prueba este ejercicio completando este código de ejemplo.
# Write clean_checkouts straight to disk
clean_checkouts.____(
CLEAN_EXPORT_PATH,
# 5,000 rows per row group
row_group_size=____,
# Streaming engine
engine="____",
)
# Confirm what landed in the Parquet file
result = pl.scan_parquet(CLEAN_EXPORT_PATH).select(
pl.len().alias("rows"),
pl.col("checkouts").sum().alias("total_checkouts"),
).collect()
print(result)