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fix: Coerce empty subquery result to NULL #30

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Merged
merged 1 commit into from
May 16, 2022
Merged

fix: Coerce empty subquery result to NULL #30

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4 changes: 2 additions & 2 deletions datafusion/core/src/execution/context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,6 @@ use crate::optimizer::to_approx_perc::ToApproxPerc;

use crate::physical_optimizer::coalesce_batches::CoalesceBatches;
use crate::physical_optimizer::merge_exec::AddCoalescePartitionsExec;
use crate::physical_optimizer::repartition::Repartition;

use crate::execution::runtime_env::{RuntimeConfig, RuntimeEnv};
use crate::logical_plan::plan::Explain;
Expand Down Expand Up @@ -1164,7 +1163,8 @@ impl SessionState {
Arc::new(AggregateStatistics::new()),
Arc::new(HashBuildProbeOrder::new()),
Arc::new(CoalesceBatches::new()),
Arc::new(Repartition::new()),
// FIXME: Repartition is temporarily disabled to avoid issues with subqueries
//Arc::new(Repartition::new()),
Arc::new(AddCoalescePartitionsExec::new()),
],
query_planner: Arc::new(DefaultQueryPlanner {}),
Expand Down
93 changes: 61 additions & 32 deletions datafusion/core/src/physical_plan/subquery.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ use std::task::{Context, Poll};

use crate::error::{DataFusionError, Result};
use crate::physical_plan::{DisplayFormatType, ExecutionPlan, Partitioning};
use arrow::array::new_null_array;
use arrow::datatypes::{Schema, SchemaRef};
use arrow::error::{ArrowError, Result as ArrowResult};
use arrow::record_batch::RecordBatch;
Expand Down Expand Up @@ -151,43 +152,71 @@ impl ExecutionPlan for SubqueryExec {
let context = context.clone();
let size_hint = stream.size_hint();
let schema = self.schema.clone();
let res_stream = stream.then(move |batch| {
let cursor = cursor.clone();
let context = context.clone();
let subqueries = subqueries.clone();
let schema = schema.clone();
async move {
let batch = batch?;
let b = Arc::new(batch.clone());
cursor.set_batch(b)?;
let mut subquery_arrays = vec![Vec::new(); subqueries.len()];
for i in 0..batch.num_rows() {
cursor.set_position(i)?;
for (subquery_i, subquery) in subqueries.iter().enumerate() {
if subquery.output_partitioning().partition_count() != 1 {
return Err(ArrowError::ComputeError(format!("Sub query should have only one partition but got {}", subquery.output_partitioning().partition_count())))
}
let mut stream = subquery.execute(0, context.clone()).await?;
let res = stream.next().await;
if let Some(subquery_batch) = res {
let subquery_batch = subquery_batch?;
if subquery_batch.column(0).len() != 1 {
return Err(ArrowError::ComputeError("Sub query should return exactly one row".to_string()))
let res_stream =
stream.then(move |batch| {
let cursor = cursor.clone();
let context = context.clone();
let subqueries = subqueries.clone();
let schema = schema.clone();
async move {
let batch = batch?;
let b = Arc::new(batch.clone());
cursor.set_batch(b)?;
let mut subquery_arrays = vec![Vec::new(); subqueries.len()];
for i in 0..batch.num_rows() {
cursor.set_position(i)?;
for (subquery_i, subquery) in subqueries.iter().enumerate() {
let null_array = || {
let schema = subquery.schema();
let fields = schema.fields();
if fields.len() != 1 {
return Err(ArrowError::ComputeError(format!(
"Sub query should have only one column but got {}",
fields.len()
)));
}

let data_type = fields.get(0).unwrap().data_type();
Ok(new_null_array(data_type, 1))
};

if subquery.output_partitioning().partition_count() != 1 {
return Err(ArrowError::ComputeError(format!(
"Sub query should have only one partition but got {}",
subquery.output_partitioning().partition_count()
)));
}
let mut stream = subquery.execute(0, context.clone()).await?;
let res = stream.next().await;
if let Some(subquery_batch) = res {
let subquery_batch = subquery_batch?;
match subquery_batch.column(0).len() {
0 => subquery_arrays[subquery_i].push(null_array()?),
1 => subquery_arrays[subquery_i]
.push(subquery_batch.column(0).clone()),
_ => return Err(ArrowError::ComputeError(
"Sub query should return no more than one row"
.to_string(),
)),
};
} else {
subquery_arrays[subquery_i].push(subquery_batch.column(0).clone());
subquery_arrays[subquery_i].push(null_array()?);
}
} else {
return Err(ArrowError::ComputeError("Sub query returned empty result set but exactly one row is expected".to_string()))
}
}
let mut new_columns = batch.columns().to_vec();
for subquery_array in subquery_arrays {
new_columns.push(concat(
subquery_array
.iter()
.map(|a| a.as_ref())
.collect::<Vec<_>>()
.as_slice(),
)?);
}
RecordBatch::try_new(schema.clone(), new_columns)
}
let mut new_columns = batch.columns().to_vec();
for subquery_array in subquery_arrays {
new_columns.push(concat(subquery_array.iter().map(|a| a.as_ref()).collect::<Vec<_>>().as_slice())?);
}
RecordBatch::try_new(schema.clone(), new_columns)
}
});
});
Ok(Box::pin(SubQueryStream {
schema: self.schema.clone(),
stream: Box::pin(res_stream),
Expand Down