Minor: improve documentation for CommonSubexprEliminate
#9700
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| /// refer to that new column. | ||
| /// | ||
| /// ```text | ||
| /// ProjectionExec(exprs=[extract (day from new_col), extract (year from new_col)]) <-- reuse here |
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Thanks @alamb just a question, so to read from the plan that Common Sub-expression Elimination optimization was applied we need to refer to new_col but how it differs from plan with projection alias but no optimization applied?
In short my question is it possible to read from the plan that optimization has been applied?
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It is possible. The optimized plan will have an obvious intermediate Projection plan that does some computation and the result will be referred later by other following plans (this pattern might occur in other reasons though
| /// refer to that new column. | ||
| /// | ||
| /// ```text | ||
| /// ProjectionExec(exprs=[extract (day from new_col), extract (year from new_col)]) <-- reuse here |
There was a problem hiding this comment.
It is possible. The optimized plan will have an obvious intermediate Projection plan that does some computation and the result will be referred later by other following plans (this pattern might occur in other reasons though
Which issue does this PR close?
Part of #7013
Rationale for this change
In the context of looking at #9678 with @wiedld it was a little unclear what the
CommonSubexprEliminatepass was doing without code explorationWhat changes are included in this PR?
Add some more description of what
CommonSubexprEliminatedoes along with an exampleAre these changes tested?
By docs CI
Are there any user-facing changes?
No, just docs