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use crate::optimizer::ApplyOrder;
use crate::{OptimizerConfig, OptimizerRule};
use datafusion_common::Result;
use datafusion_expr::expr::Sort as ExprSort;
use datafusion_expr::logical_plan::LogicalPlan;
use datafusion_expr::{Expr, Sort};
use hashbrown::HashSet;
#[derive(Default)]
pub struct EliminateDuplicatedExpr;
impl EliminateDuplicatedExpr {
#[allow(missing_docs)]
pub fn new() -> Self {
Self {}
}
}
impl OptimizerRule for EliminateDuplicatedExpr {
fn try_optimize(
&self,
plan: &LogicalPlan,
_config: &dyn OptimizerConfig,
) -> Result<Option<LogicalPlan>> {
match plan {
LogicalPlan::Sort(sort) => {
let normalized_sort_keys = sort
.expr
.iter()
.map(|e| match e {
Expr::Sort(ExprSort { expr, .. }) => {
Expr::Sort(ExprSort::new(expr.clone(), true, false))
}
_ => e.clone(),
})
.collect::<Vec<_>>();
let mut dedup_expr = Vec::new();
let mut dedup_set = HashSet::new();
sort.expr.iter().zip(normalized_sort_keys.iter()).for_each(
|(expr, normalized_expr)| {
if !dedup_set.contains(normalized_expr) {
dedup_expr.push(expr);
dedup_set.insert(normalized_expr);
}
},
);
if dedup_expr.len() == sort.expr.len() {
Ok(None)
} else {
Ok(Some(LogicalPlan::Sort(Sort {
expr: dedup_expr.into_iter().cloned().collect::<Vec<_>>(),
input: sort.input.clone(),
fetch: sort.fetch,
})))
}
}
_ => Ok(None),
}
}
fn name(&self) -> &str {
"eliminate_duplicated_expr"
}
fn apply_order(&self) -> Option<ApplyOrder> {
Some(ApplyOrder::TopDown)
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::test::*;
use datafusion_expr::{col, logical_plan::builder::LogicalPlanBuilder};
use std::sync::Arc;
fn assert_optimized_plan_eq(plan: &LogicalPlan, expected: &str) -> Result<()> {
crate::test::assert_optimized_plan_eq(
Arc::new(EliminateDuplicatedExpr::new()),
plan,
expected,
)
}
#[test]
fn eliminate_sort_expr() -> Result<()> {
let table_scan = test_table_scan().unwrap();
let plan = LogicalPlanBuilder::from(table_scan)
.sort(vec![col("a"), col("a"), col("b"), col("c")])?
.limit(5, Some(10))?
.build()?;
let expected = "Limit: skip=5, fetch=10\
\n Sort: test.a, test.b, test.c\
\n TableScan: test";
assert_optimized_plan_eq(&plan, expected)
}
#[test]
fn eliminate_sort_exprs_with_options() -> Result<()> {
let table_scan = test_table_scan().unwrap();
let sort_exprs = vec![
col("a").sort(true, true),
col("b").sort(true, false),
col("a").sort(false, false),
col("b").sort(false, true),
];
let plan = LogicalPlanBuilder::from(table_scan)
.sort(sort_exprs)?
.limit(5, Some(10))?
.build()?;
let expected = "Limit: skip=5, fetch=10\
\n Sort: test.a ASC NULLS FIRST, test.b ASC NULLS LAST\
\n TableScan: test";
assert_optimized_plan_eq(&plan, expected)
}
}