Explain multiple LazyFrames as if passed to pl$collect_all()

Source code

Description

Common Subplan Elimination is applied on the combined plan, meaning that diverging queries will run only once.

Usage

pl$explain_all(lazy_frames, ..., optimizations = pl\$QueryOptFlags())

Arguments

lazy_frames	A list of LazyFrames to collect.
…	These dots are for future extensions and must be empty.
optimizations	A QueryOptFlags object to indicate optimization passes done during query optimization.

Value

A character value containing the query plan.

Examples

library("polars")

lf <- as_polars_lf(mtcars)$with_columns(sqrt_mpg = pl$col("mpg")$sqrt())

cyl_4 <- lf$filter(pl$col("cyl") == 4)
cyl_6 <- lf$filter(pl$col("cyl") == 6)

# Note that `sqrt_mpg` is present in the plans for `cyl_4` and `cyl_6` but
# only once in the plan produced by `pl$explain_all()`. This is because
# `pl$explain_all()` eliminates parts of the queries that are shared across
# multiple plans.
pl$explain_all(list(cyl_4, cyl_6)) |>
  writeLines()

#> SINK_MULTIPLE
#>   PLAN 0:
#>      WITH_COLUMNS:
#>      [col("mpg").sqrt().alias("sqrt_mpg")] 
#>       FILTER [(col("cyl")) == (4.0)]
#>       FROM
#>         DF ["mpg", "cyl", "disp", "hp", ...]; PROJECT */11 COLUMNS
#>   PLAN 1:
#>      WITH_COLUMNS:
#>      [col("mpg").sqrt().alias("sqrt_mpg")] 
#>       FILTER [(col("cyl")) == (6.0)]
#>       FROM
#>         DF ["mpg", "cyl", "disp", "hp", ...]; PROJECT */11 COLUMNS
#> END SINK_MULTIPLE