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https://issues.apache.org/jira/browse/ARROW-7866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17038490#comment-17038490
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Istvan Szukacs commented on ARROW-7866:
---------------------------------------
Thanks [~andygrove], with your help I was able to have the value correctly
printed.
{{let retf1 = batch.column(0).as_any().downcast_ref::<UInt64Array>().unwrap();}}
{{println!("P: \{:?}", retf1.value(0));}}
> [Rust] How to handle aggregates with Datafusion?
> ------------------------------------------------
>
> Key: ARROW-7866
> URL: https://issues.apache.org/jira/browse/ARROW-7866
> Project: Apache Arrow
> Issue Type: Bug
> Components: Rust - DataFusion
> Affects Versions: 0.16.0
> Reporter: Istvan Szukacs
> Priority: Minor
>
> Hi,
> I am trying to use the Rust tools and I was running into this interesting
> behavior.
> {code}
> use std::sync::Arc;
> extern crate arrow;
> extern crate datafusion;
> use arrow::array::\{StringArray, UInt32Array};
> use arrow::datatypes::\{DataType, Field, Schema};
> use datafusion::error::Result;
> use datafusion::execution::context::ExecutionContext;
> fn main() -> Result<()> {
> // create local execution context
> let mut ctx = ExecutionContext::new();
> // define schema for data source (csv file)
> let schema = Arc::new(Schema::new(vec![
> Field::new("index", DataType::UInt32, false),
> Field::new("tablename", DataType::Utf8, false),
> Field::new("datetime", DataType::Utf8, false),
> Field::new("partition", DataType::Utf8, false),
> Field::new("fileSize", DataType::UInt32, false),
> ]));
> // register csv file with the execution context
> ctx.register_csv(
> "awesome_table",
> &format!(
> "../tableMetaData/anon/{}",
> "013ff3245cc90a3394943da0b6552b9f98313288e0a174f94f8dcb10.csv"
> ),
> &schema,
> true,
> );
> let sql = "SELECT COUNT(partition) FROM awesome_table";
> // create the query plan
> let plan = ctx.create_logical_plan(&sql)?;
> let plan = ctx.optimize(&plan)?;
> let plan = ctx.create_physical_plan(&plan, 1024 * 1024)?;
> // execute the query
> let results = ctx.collect(plan.as_ref())?;
> // iterate over the results
> results.iter().for_each(|batch| {
> println!(
> "RecordBatch has {} rows and {} columns",
> batch.num_rows(),
> batch.num_columns()
> );
> let retf1 = batch.column(0).as_any().downcast_ref::<StringArray>();
> match retf1 {
> Some(_) => println!("Some retf1"),
> None => println!("None retf1"),
> }
> let retf2 = batch.column(1).as_any().downcast_ref::<StringArray>();
> match retf2 {
> Some(_) => println!("Some retf2"),
> None => println!("None retf2"),
> }
>
> // for i in 0..batch.num_rows() {
> // println!("P: {}", pcnt.value(i));
> // }
> });
> Ok(())
> }
> {code}
>
>
> {code}
> cargo build --release && ./target/release/cli
> RecordBatch has 1 rows and 1 columns
> RecordBatch has 1 rows and 2 columns
> None retf1
> None retf2
> {code}
>
> In case of no aggregation:
>
> {code}
> let sql = "SELECT index FROM awesome_table";
> // create the query plan
> let plan = ctx.create_logical_plan(&sql)?;
> let plan = ctx.optimize(&plan)?;
> let plan = ctx.create_physical_plan(&plan, 1024 * 1024)?;
> // execute the query
> let results = ctx.collect(plan.as_ref())?;
> // iterate over the results
> results.iter().for_each(|batch| {
> println!(
> "RecordBatch has {} rows and {} columns",
> batch.num_rows(),
> batch.num_columns(),
> );
> let retf1 = batch.column(0).as_any().downcast_ref::<UInt32Array>();
> match retf1 {
> Some(_) => println!("Some retf1"),
> None => println!("None retf1"),
> }
> // let retf2 = batch.column(1).as_any().downcast_ref::<UInt32Array>();
> // match retf2 {
> // Some(_) => println!("Some retf2"),
> // None => println!("None retf2"),
> // }
> for i in 0..batch.num_rows() {
> println!("P: {}", retf1.unwrap().value(i));
> }
> });
> Ok(())
> }
> {code}
>
> {code}
>
> P: 126436
> P: 126437
> P: 126438
> P: 126439
> P: 126440
> P: 126441
> {code}
>
> Is there a way to access the fields when aggregating?
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