fix: don't unifies projection if expr is non-trival #8454
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alamb
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Dec 7, 2023
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Thank you for the contribution @haohuaijin . This change makes sense to me
cc @mustafasrepo and @Dandandan
| let mut column_ref_map: HashMap<Column, usize> = HashMap::new(); | ||
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| // Collect the column references usage in the outer projection. | ||
| projection.expr().iter().for_each(|(expr, _)| { |
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I may be mistaken and it may not matter, but I think this will prevent pushing down exprs that refer to the same column more than once
Projection exprs=[b as c, b as d]
Projection exprs = [a as b]
Into
Projection exprs=[a as c, a as d]
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We don't prevent Column and Literal push_down. We prevent other express push_down, used to prevent multiple evaluation of the same expression.
if column_ref_map.iter().any(|(column, count)| {
*count > 1 && !is_expr_trivial(&child.expr()[column.index()].0.clone())
}) {
return Ok(None);
}
mustafasrepo
approved these changes
Dec 8, 2023
Weijun-H
reviewed
Dec 8, 2023
Co-authored-by: Alex Huang <huangweijun1001@gmail.com>
|
Thank you @haohuaijin,. @Weijun-H and @mustafasrepo |
appletreeisyellow
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Dec 15, 2023
* fix: don't unifies projection if expr is non-trival * Update datafusion/core/src/physical_optimizer/projection_pushdown.rs Co-authored-by: Alex Huang <huangweijun1001@gmail.com> --------- Co-authored-by: Alex Huang <huangweijun1001@gmail.com>
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Which issue does this PR close?
Closes #8453
Rationale for this change
What changes are included in this PR?
don't unifies projection if the expression in non-trival. see discussion in #8296
Are these changes tested?
Are there any user-facing changes?
add physical plan check in
.slttest