Remove unnecessary projection in logical plan optimization phase #747
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Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
houqp
approved these changes
Jul 18, 2021
alamb
approved these changes
Jul 19, 2021
| @@ -496,6 +506,60 @@ mod tests { | |||
| Ok(()) | |||
| } | |||
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| #[test] | |||
| fn redundunt_project() -> Result<()> { | |||
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Suggested change
| fn redundunt_project() -> Result<()> { | |
| fn redundant_project() -> Result<()> { |
| } | ||
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| #[test] | ||
| fn noncontiguous_redundunt_projection() -> Result<()> { |
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Suggested change
| fn noncontiguous_redundunt_projection() -> Result<()> { | |
| fn noncontiguous_redundant_projection() -> Result<()> { |
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Which issue does this PR close?
Related to #277 .
What changes are included in this PR?
This PR adds an optimization rule to remove unnecessary projection plans.
We'll consider a projection as "unnecessary" if it only reorders columns (requires the same columns against its sub-plan) and is not the first projection.
For the case where the sub-plan of a projection is a table scan, projection will be pushed down into the table scan plan as a
Vec<usize>array. From the documentation, this array should be ordered. So I keep the projection in this situation (test casereorder_projection()).