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https://issues.apache.org/jira/browse/ARROW-17462?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated ARROW-17462:
-----------------------------------
Labels: pull-request-available (was: )
> [R] Cast scalars to type of field in Expression building
> --------------------------------------------------------
>
> Key: ARROW-17462
> URL: https://issues.apache.org/jira/browse/ARROW-17462
> Project: Apache Arrow
> Issue Type: Improvement
> Components: R
> Reporter: Neal Richardson
> Assignee: Neal Richardson
> Priority: Major
> Labels: pull-request-available
> Fix For: 10.0.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> After looking at the ExecPlan output of some queries, it jumped out at me how
> we translate {{ int_field == 5 }} in R as {{ cast(int_field, float64) == 5 }}
> because 5 is a double in R.
> This extra work has a noticeable performance impact. Here's a simple query on
> the taxi dataset, filtering down to 54 out of 1.5 billion rows and selecting
> a single column. My idea was to make a query that does not much other than
> evaluate the filter.
> {code}
> > system.time(ds |> select(passenger_count) |> filter(passenger_count > 10)
> > |> compute())
> user system elapsed
> 0.391 0.024 0.362
> > system.time(ds |> select(passenger_count) |> filter(passenger_count >
> > Scalar$create(10, type = int8())) |> compute())
> user system elapsed
> 0.206 0.025 0.179
> {code}
> You can see the difference in the query plans too:
> {code}
> > ds |> select(passenger_count) |> filter(passenger_count > 10) |> explain()
> ExecPlan with 4 nodes:
> 3:SinkNode{}
> 2:ProjectNode{projection=[passenger_count]}
> 1:FilterNode{filter=(cast(passenger_count, {to_type=double,
> allow_int_overflow=false, allow_time_truncate=false,
> allow_time_overflow=false, allow_decimal_truncate=false,
> allow_float_truncate=false, allow_invalid_utf8=false}) > 10)}
> 0:SourceNode{}
> > ds |> select(passenger_count) |> filter(passenger_count > Scalar$create(10,
> > type = int8())) |> explain()
> ExecPlan with 4 nodes:
> 3:SinkNode{}
> 2:ProjectNode{projection=[passenger_count]}
> 1:FilterNode{filter=(passenger_count > 10)}
> 0:SourceNode{}
> {code}
> Ideally Acero would do this more intelligently (cf. ARROW-11402), but we
> should also be able to do smarter things when assembling the Expression in R.
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