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Fix: common_sub_expression_eliminate optimizer rule failed #16066

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Merged
merged 4 commits into from
Sep 28, 2025
Merged

Fix: common_sub_expression_eliminate optimizer rule failed #16066

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6936394
Fix: common_sub_expression_eliminate optimizer rule failed
Col-Waltz May 16, 2025
f5b6a24
Merge branch 'main' into fix_common_subexpression_eliminate
alamb Jul 28, 2025
416e585
Merge branch 'main' into fix_common_subexpression_eliminate
alamb Aug 26, 2025
182c655
Merge branch 'main' into fix_common_subexpression_eliminate
alamb Sep 25, 2025
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26 changes: 24 additions & 2 deletions datafusion/optimizer/src/common_subexpr_eliminate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -316,6 +316,19 @@ impl CommonSubexprEliminate {
} => {
let rewritten_aggr_expr = new_exprs_list.pop().unwrap();
let new_aggr_expr = original_exprs_list.pop().unwrap();
let saved_names = if let Some(aggr_expr) = aggr_expr {
let name_preserver = NamePreserver::new_for_projection();
aggr_expr
.iter()
.map(|expr| Some(name_preserver.save(expr)))
.collect::<Vec<_>>()
} else {
new_aggr_expr
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Is this the same as a vec of all None?

vec![None; new_agg_expr.len()]`

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@Col-Waltz Col-Waltz May 16, 2025 •
edited
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Yes it is, thanks for the comment. But this will not work, because vec! requires value to implement Clone trait but the Option<SavedName> doesn't. It seems to me easier to do this by map instead of adding trait to SavedName.

.clone()
.into_iter()
.map(|_| None)
.collect::<Vec<_>>()
};

let mut agg_exprs = common_exprs
.into_iter()
Expand All @@ -326,10 +339,19 @@ impl CommonSubexprEliminate {
for expr in &new_group_expr {
extract_expressions(expr, &mut proj_exprs)
}
for (expr_rewritten, expr_orig) in
rewritten_aggr_expr.into_iter().zip(new_aggr_expr)
for ((expr_rewritten, expr_orig), saved_name) in
rewritten_aggr_expr
.into_iter()
.zip(new_aggr_expr)
.zip(saved_names)
{
if expr_rewritten == expr_orig {
let expr_rewritten = if let Some(saved_name) = saved_name
{
saved_name.restore(expr_rewritten)
} else {
expr_rewritten
};
if let Expr::Alias(Alias { expr, name, .. }) =
expr_rewritten
{
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25 changes: 25 additions & 0 deletions datafusion/sqllogictest/test_files/aggregate.slt
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Original file line number Diff line number Diff line change
Expand Up @@ -739,6 +739,31 @@ SELECT c2, var_samp(c12) FILTER (WHERE c12 > 0.95) FROM aggregate_test_100 GROUP
4 NULL
5 NULL

statement ok
CREATE TABLE t (
a DOUBLE,
b BIGINT,
c INT
) AS VALUES
(1.0, 10, -5),
(2.0, 20, -5),
(3.0, 20, 4);

# https://github.com/apache/datafusion/issues/15291
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for some reason this query is failing for me

> WITH s AS (
    SELECT
        COUNT(a) FILTER (WHERE (b * b) - 3600 <= b),
	COUNT(a) FILTER (WHERE (b * b) - 3000 <= b AND (c >= 0)),
	COUNT(a) FILTER (WHERE (b * b) - 3000 <= b AND (c >= 0) AND (c >= 0))
    FROM t
) SELECT * FROM s;  🤔 Invalid statement: SQL error: ParserError("Expected: ), found: ( at Line: 3, Column: 25")

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Nm, I can get it to reproduce like this

> set datafusion.sql_parser.dialect = 'postgres';
0 row(s) fetched.
Elapsed 0.000 seconds.

> CREATE TABLE t (
  a DOUBLE,
  b BIGINT,
  c INT
) AS VALUES
(1.0, 10, -5),
(2.0, 20, -5),
(3.0, 20, 4);
0 row(s) fetched.
Elapsed 0.002 seconds.

> WITH s AS (
    SELECT
        COUNT(a) FILTER (WHERE (b * b) - 3600 <= b),
	COUNT(a) FILTER (WHERE (b * b) - 3000 <= b AND (c >= 0)),
	COUNT(a) FILTER (WHERE (b * b) - 3000 <= b AND (c >= 0) AND (c >= 0))
    FROM t
) SELECT * FROM s
;
Optimizer rule 'common_sub_expression_eliminate' failed
caused by
Schema error: No field named "count(t.a) FILTER (WHERE t.b * t.b - Int64(3600) <= t.b)". Did you mean 'count(t.a) FILTER (WHERE __common_expr_1 AS t.b * t.b - Int64(3600) <= t.b)'?.

query III
WITH s AS (
SELECT
COUNT(a) FILTER (WHERE (b * b) - 3600 <= b),
COUNT(a) FILTER (WHERE (b * b) - 3000 <= b AND (c >= 0)),
COUNT(a) FILTER (WHERE (b * b) - 3000 <= b AND (c >= 0) AND (c >= 0))
FROM t
) SELECT * FROM s
----
3 1 1

statement ok
DROP TABLE t

# Restore the default dialect
statement ok
set datafusion.sql_parser.dialect = 'Generic';
Expand Down