Print the optimized or non-optimized plans of LazyFrame

Source code

Description

$describe_plan() shows the query in the format that polars understands. $describe_optimized_plan() shows the optimized query plan that polars will execute when $collect() is called. It is possible that both plans are identical if polars doesn’t find any way to optimize the query.

Usage

<LazyFrame>$describe_optimized_plan()

LazyFrame_describe_plan()

Value

This only prints the plan in the console, it doesn’t return any value.

Examples

library(polars)

lazy_frame = pl$LazyFrame(iris)

# Prepare your query
lazy_query = lazy_frame$sort("Species")$filter(pl$col("Species") != "setosa")

# This is the query as `polars` understands it
lazy_query$describe_plan()

#> FILTER [(col("Species")) != (String(setosa))] FROM
#>   SORT BY [col("Species")]
#>     DF ["Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width"]; PROJECT */5 COLUMNS; SELECTION: None

#> $ok
#> NULL
#> 
#> $err
#> NULL
#> 
#> attr(,"class")
#> [1] "extendr_result"

# This is the query after `polars` optimizes it: instead of sorting first and
# then filtering, it is faster to filter first and then sort the rest.
lazy_query$describe_optimized_plan()

#> SORT BY [col("Species")]
#>   DF ["Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width"]; PROJECT */5 COLUMNS; SELECTION: [(col("Species")) != (String(setosa))]