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Merged
merged 4 commits into from
Nov 19, 2021
Merged

Optimize the performance queries with a single distinct aggregate #1315

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af56862
add single_distinct_to_group_by optimizer rule
Nov 16, 2021
c9f0ac0
add single_distinct_to_group_by optimizer rule
Nov 17, 2021
dd5c5a3
Merge branch 'master' into single_distinct
ic4y Nov 17, 2021
7f4cf11
Fix a test method and support multiple aggregateFunction
Nov 18, 2021
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104 changes: 74 additions & 30 deletions datafusion/src/optimizer/single_distinct_to_groupby.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,24 +22,23 @@ use crate::execution::context::ExecutionProps;
use crate::logical_plan::{columnize_expr, DFSchema, Expr, LogicalPlan};
use crate::optimizer::optimizer::OptimizerRule;
use crate::optimizer::utils;
use hashbrown::HashSet;
use std::sync::Arc;

/// single distinct to group by optimizer rule
/// - Aggregation
/// GROUP BY (k)
/// F1(DISTINCT s)
/// - X
/// ```text
/// SELECT F1(DISTINCT s),F2(DISTINCT s)
/// ...
/// GROUP BY k
///
/// into
/// Into
///
/// - Aggregation
/// GROUP BY (k)
/// F1(s)
/// - Aggregation
/// GROUP BY (k, s)
/// - X
/// </pre>
/// <p>
/// SELECT F1(s),F2(s)
/// FROM (
/// SELECT s, k ... GROUP BY s, k
/// )
/// GROUP BY k
/// ```
pub struct SingleDistinctToGroupBy {}

impl SingleDistinctToGroupBy {
Expand All @@ -58,14 +57,19 @@ fn optimize(plan: &LogicalPlan) -> Result<LogicalPlan> {
group_expr,
} => {
if is_single_distinct_agg(plan) {
let mut all_group_args = Vec::with_capacity(group_expr.len());
all_group_args.append(&mut group_expr.clone());
let mut group_fields_set = HashSet::new();
let mut all_group_args = group_expr.clone();
// remove distinct and collection args
let new_aggr_expr = aggr_expr
.iter()
.map(|agg_expr| match agg_expr {
Expr::AggregateFunction { fun, args, .. } => {
all_group_args.append(&mut args.clone());
// is_single_distinct_agg ensure args.len=1
if group_fields_set
.insert(args[0].name(input.schema()).unwrap())
{
all_group_args.push(args[0].clone());
}
Expr::AggregateFunction {
fun: fun.clone(),
args: args.clone(),
Expand Down Expand Up @@ -102,11 +106,12 @@ fn optimize(plan: &LogicalPlan) -> Result<LogicalPlan> {

let final_agg = LogicalPlan::Aggregate {
input: Arc::new(grouped_agg.unwrap()),
group_expr: group_expr.clone(),
aggr_expr: new_aggr_expr,
schema: final_agg_schema.clone(),
group_expr: group_expr.clone(),
};

//so the aggregates are displayed in the same way even after the rewrite
let mut alias_expr: Vec<Expr> = Vec::new();
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@alamb alamb Nov 17, 2021

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It might help here to explain the rationale for adding this alias (so the aggregates are displayed in the same way even after the rewrite). It is important but may not be obvious to other readers

final_agg
.expressions()
Expand Down Expand Up @@ -145,19 +150,25 @@ fn optimize_children(plan: &LogicalPlan) -> Result<LogicalPlan> {

fn is_single_distinct_agg(plan: &LogicalPlan) -> bool {
match plan {
LogicalPlan::Aggregate { aggr_expr, .. } => {
aggr_expr.len() == 1
&& aggr_expr
.iter()
.filter(|expr| {
let mut is_distinct = false;
if let Expr::AggregateFunction { distinct, .. } = expr {
is_distinct = *distinct;
}
is_distinct
})
.count()
== 1
LogicalPlan::Aggregate {
input, aggr_expr, ..
} => {
let mut fields_set = HashSet::new();
aggr_expr
.iter()
.filter(|expr| {
let mut is_distinct = false;
if let Expr::AggregateFunction { distinct, args, .. } = expr {
is_distinct = *distinct;
args.iter().for_each(|expr| {
fields_set.insert(expr.name(input.schema()).unwrap());
})
}
is_distinct
})
.count()
== aggr_expr.len()
&& fields_set.len() == 1
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@alamb alamb Nov 18, 2021

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👍

}
_ => false,
}
Expand All @@ -180,6 +191,7 @@ impl OptimizerRule for SingleDistinctToGroupBy {
mod tests {
use super::*;
use crate::logical_plan::{col, count, count_distinct, max, LogicalPlanBuilder};
use crate::physical_plan::aggregates;
use crate::test::*;

fn assert_optimized_plan_eq(plan: &LogicalPlan, expected: &str) {
Expand All @@ -199,6 +211,7 @@ mod tests {
.aggregate(Vec::<Expr>::new(), vec![max(col("b"))])?
.build()?;

// Do nothing
let expected = "Aggregate: groupBy=[[]], aggr=[[MAX(#test.b)]] [MAX(test.b):UInt32;N]\
\n TableScan: test projection=None [a:UInt32, b:UInt32, c:UInt32]";

Expand All @@ -214,6 +227,7 @@ mod tests {
.aggregate(Vec::<Expr>::new(), vec![count_distinct(col("b"))])?
.build()?;

// Should work
let expected = "Projection: #COUNT(test.b) AS COUNT(DISTINCT test.b) [COUNT(DISTINCT test.b):UInt64;N]\
\n Aggregate: groupBy=[[]], aggr=[[COUNT(#test.b)]] [COUNT(test.b):UInt64;N]\
\n Aggregate: groupBy=[[#test.b]], aggr=[[]] [b:UInt32]\
Expand All @@ -231,6 +245,7 @@ mod tests {
.aggregate(vec![col("a")], vec![count_distinct(col("b"))])?
.build()?;

// Should work
let expected = "Projection: #test.a AS a, #COUNT(test.b) AS COUNT(DISTINCT test.b) [a:UInt32, COUNT(DISTINCT test.b):UInt64;N]\
\n Aggregate: groupBy=[[#test.a]], aggr=[[COUNT(#test.b)]] [a:UInt32, COUNT(test.b):UInt64;N]\
\n Aggregate: groupBy=[[#test.a, #test.b]], aggr=[[]] [a:UInt32, b:UInt32]\
Expand All @@ -251,13 +266,41 @@ mod tests {
)?
.build()?;

// Do nothing
let expected = "Aggregate: groupBy=[[#test.a]], aggr=[[COUNT(DISTINCT #test.b), COUNT(DISTINCT #test.c)]] [a:UInt32, COUNT(DISTINCT test.b):UInt64;N, COUNT(DISTINCT test.c):UInt64;N]\
\n TableScan: test projection=None [a:UInt32, b:UInt32, c:UInt32]";

assert_optimized_plan_eq(&plan, expected);
Ok(())
}

#[test]
fn one_field_two_distinct_and_groupby() -> Result<()> {
let table_scan = test_table_scan()?;

let plan = LogicalPlanBuilder::from(table_scan)
.aggregate(
vec![col("a")],
vec![
count_distinct(col("b")),
Expr::AggregateFunction {
fun: aggregates::AggregateFunction::Max,
distinct: true,
args: vec![col("b")],
},
],
)?
.build()?;
// Should work
let expected = "Projection: #test.a AS a, #COUNT(test.b) AS COUNT(DISTINCT test.b), #MAX(test.b) AS MAX(DISTINCT test.b) [a:UInt32, COUNT(DISTINCT test.b):UInt64;N, MAX(DISTINCT test.b):UInt32;N]\
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@alamb alamb Nov 18, 2021

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nice

\n Aggregate: groupBy=[[#test.a]], aggr=[[COUNT(#test.b), MAX(#test.b)]] [a:UInt32, COUNT(test.b):UInt64;N, MAX(test.b):UInt32;N]\
\n Aggregate: groupBy=[[#test.a, #test.b]], aggr=[[]] [a:UInt32, b:UInt32]\
\n TableScan: test projection=None [a:UInt32, b:UInt32, c:UInt32]";

assert_optimized_plan_eq(&plan, expected);
Ok(())
}

#[test]
fn distinct_and_common() -> Result<()> {
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@alamb alamb Nov 17, 2021

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👍

let table_scan = test_table_scan()?;
Expand All @@ -269,6 +312,7 @@ mod tests {
)?
.build()?;

// Do nothing
let expected = "Aggregate: groupBy=[[#test.a]], aggr=[[COUNT(DISTINCT #test.b), COUNT(#test.c)]] [a:UInt32, COUNT(DISTINCT test.b):UInt64;N, COUNT(test.c):UInt64;N]\
\n TableScan: test projection=None [a:UInt32, b:UInt32, c:UInt32]";

Expand Down
6 changes: 3 additions & 3 deletions datafusion/tests/user_defined_plan.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -217,9 +217,9 @@ async fn topk_plan() -> Result<()> {
let mut ctx = setup_table(make_topk_context()).await?;

let expected = vec![
"| logical_plan after topk | TopK: k=3 |",
"| | Projection: #sales.customer_id, #sales.revenue |",
"| | TableScan: sales projection=Some([0, 1]) |",
"| logical_plan after topk | TopK: k=3 |",
"| | Projection: #sales.customer_id, #sales.revenue |",
"| | TableScan: sales projection=Some([0, 1]) |",
].join("\n");

let explain_query = format!("EXPLAIN VERBOSE {}", QUERY);
Expand Down