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implement rewrite for ExtractEquijoinPredicate and avoid clone in filter #10165

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merged 3 commits into from
Apr 22, 2024
Merged

implement rewrite for ExtractEquijoinPredicate and avoid clone in filter #10165

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9de163f
implement rewrite for ExtractEquijoinPredicate and avoid clone in filter
Lordworms Apr 21, 2024
48a4d20
fix clippy
Lordworms Apr 21, 2024
164c0e2
optimize code
Lordworms Apr 22, 2024
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130 changes: 91 additions & 39 deletions datafusion/optimizer/src/extract_equijoin_predicate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,9 +18,11 @@
//! [`ExtractEquijoinPredicate`] identifies equality join (equijoin) predicates
use crate::optimizer::ApplyOrder;
use crate::{OptimizerConfig, OptimizerRule};
use datafusion_common::DFSchema;
use datafusion_common::tree_node::Transformed;
use datafusion_common::Result;
use datafusion_expr::utils::{can_hash, find_valid_equijoin_key_pair, split_conjunction};
use datafusion_common::{internal_err, DFSchema};
use datafusion_expr::expr::Alias;
use datafusion_expr::utils::{can_hash, find_valid_equijoin_key_pair};
use datafusion_expr::{BinaryExpr, Expr, ExprSchemable, Join, LogicalPlan, Operator};
use std::sync::Arc;

Expand Down Expand Up @@ -51,14 +53,33 @@ impl ExtractEquijoinPredicate {
impl OptimizerRule for ExtractEquijoinPredicate {
fn try_optimize(
&self,
plan: &LogicalPlan,
_plan: &LogicalPlan,
_config: &dyn OptimizerConfig,
) -> Result<Option<LogicalPlan>> {
internal_err!("Should have called ExtractEquijoinPredicate::rewrite")
}
fn supports_rewrite(&self) -> bool {
true
}

fn name(&self) -> &str {
"extract_equijoin_predicate"
}

fn apply_order(&self) -> Option<ApplyOrder> {
Some(ApplyOrder::BottomUp)
}

fn rewrite(
&self,
plan: LogicalPlan,
_config: &dyn OptimizerConfig,
) -> Result<Transformed<LogicalPlan>> {
match plan {
LogicalPlan::Join(Join {
left,
right,
on,
mut on,
filter,
join_type,
join_constraint,
Expand All @@ -67,66 +88,97 @@ impl OptimizerRule for ExtractEquijoinPredicate {
}) => {
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You might be able to avoid a level of indenting if you did the entire match here, like:

 match plan {
            LogicalPlan::Join(Join {
                left,
                right,
                mut on,
                filter: Some(expr),
                join_type,
                join_constraint,
            }) => {

Then you could avoid reassembling LogicalPlan::Join as well

let left_schema = left.schema();
let right_schema = right.schema();

filter.as_ref().map_or(Result::Ok(None), |expr| {
if let Some(expr) = filter {
let (equijoin_predicates, non_equijoin_expr) =
split_eq_and_noneq_join_predicate(
expr,
left_schema,
right_schema,
)?;

let optimized_plan = (!equijoin_predicates.is_empty()).then(|| {
let mut new_on = on.clone();
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here to avoid clone of vector on

new_on.extend(equijoin_predicates);

LogicalPlan::Join(Join {
left: left.clone(),
right: right.clone(),
on: new_on,
Comment on lines -84 to -86
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here to avoid clone of arc

if !equijoin_predicates.is_empty() {
on.extend(equijoin_predicates);
Ok(Transformed::yes(LogicalPlan::Join(Join {
left,
right,
on,
filter: non_equijoin_expr,
join_type,
join_constraint,
schema,
null_equals_null,
})))
} else {
Ok(Transformed::no(LogicalPlan::Join(Join {
left,
right,
on,
filter: non_equijoin_expr,
join_type: *join_type,
join_constraint: *join_constraint,
schema: schema.clone(),
null_equals_null: *null_equals_null,
})
});

Ok(optimized_plan)
})
join_type,
join_constraint,
schema,
null_equals_null,
})))
}
} else {
Ok(Transformed::no(LogicalPlan::Join(Join {
left,
right,
on,
filter,
join_type,
join_constraint,
schema,
null_equals_null,
})))
}
}
_ => Ok(None),
_ => Ok(Transformed::no(plan)),
}
}
}

fn name(&self) -> &str {
"extract_equijoin_predicate"
}
/// split with ownership
fn split_conjunction_own(expr: Expr) -> Vec<Expr> {
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@Lordworms Lordworms Apr 21, 2024 •
edited
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here implement a ownership version of split conjunction to avoid clone while passing reference

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I think there is already a function that does this: https://docs.rs/datafusion/latest/datafusion/logical_expr/utils/fn.split_conjunction_owned.html

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ok got it

split_conjunction_own_impl(expr, vec![])
}

fn apply_order(&self) -> Option<ApplyOrder> {
Some(ApplyOrder::BottomUp)
fn split_conjunction_own_impl(expr: Expr, mut exprs: Vec<Expr>) -> Vec<Expr> {
match expr {
Expr::BinaryExpr(BinaryExpr {
right,
op: Operator::And,
left,
}) => {
let mut left_exprs = split_conjunction_own_impl(*left, vec![]);
let mut right_exprs = split_conjunction_own_impl(*right, vec![]);
left_exprs.append(&mut right_exprs);
left_exprs
}
Expr::Alias(Alias { expr, .. }) => split_conjunction_own_impl(*expr, exprs),
other => {
exprs.push(other);
exprs
}
}
}

fn split_eq_and_noneq_join_predicate(
filter: &Expr,
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here we directly split filter to avoid further clone

filter: Expr,
left_schema: &Arc<DFSchema>,
right_schema: &Arc<DFSchema>,
) -> Result<(Vec<EquijoinPredicate>, Option<Expr>)> {
let exprs = split_conjunction(filter);
let exprs = split_conjunction_own(filter);

let mut accum_join_keys: Vec<(Expr, Expr)> = vec![];
let mut accum_filters: Vec<Expr> = vec![];
for expr in exprs {
match expr {
Expr::BinaryExpr(BinaryExpr {
left,
ref left,
op: Operator::Eq,
right,
ref right,
}) => {
let left = left.as_ref();
let right = right.as_ref();

let join_key_pair = find_valid_equijoin_key_pair(
left,
right,
Expand All @@ -141,13 +193,13 @@ fn split_eq_and_noneq_join_predicate(
if can_hash(&left_expr_type) && can_hash(&right_expr_type) {
accum_join_keys.push((left_expr, right_expr));
} else {
accum_filters.push(expr.clone());
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avoid clone

accum_filters.push(expr);
}
} else {
accum_filters.push(expr.clone());
accum_filters.push(expr);
}
}
_ => accum_filters.push(expr.clone()),
_ => accum_filters.push(expr),
}
}

Expand Down