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https://issues.apache.org/jira/browse/ARROW-9770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17182860#comment-17182860
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Jorge edited comment on ARROW-9770 at 8/23/20, 9:51 PM:
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That is a cool idea. It seems to be a case of algebraic simplification. Maybe
there is already a rust library that can do that work for us?
was (Author: jorgecarleitao):
That is a cool idea. It seems to be a case of algebraic simplication. Maybe
there is already a rust library that can do that work for us?
> [Rust] [DataFusion] Add constant folding to expressions during logically
> planning
> ---------------------------------------------------------------------------------
>
> Key: ARROW-9770
> URL: https://issues.apache.org/jira/browse/ARROW-9770
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Rust, Rust - DataFusion
> Reporter: Andrew Lamb
> Priority: Minor
>
> The high level idea is that if an expression can be partially evaluated
> during planning time then
> # The execution time will be increased
> # There may be additional optimizations possible (like removing entire
> LogicalPlan nodes, for example)
> I recently saw the following selection expression created (by the [predicate
> push down|https://github.com/apache/arrow/pull/7880])
> {code}
> Selection: #a Eq Int64(1) And #b GtEq Int64(1) And #a LtEq Int64(1) And #a Eq
> Int64(1) And #b GtEq Int64(1) And #a LtEq Int64(1)
> TableScan: test projection=None
> {code}
> This could be simplified significantly:
> 1. Duplicate clauses could be removed (e.g. `#a Eq Int64(1) And #a Eq
> Int64(1)` --> `#a Eq Int64(1)`)
> 2. Algebraic simplification (e.g. if `A<=B and A=5`, is the same as `A=5`)
> Inspiration can be taken from the postgres code that evaluates constant
> expressions
> https://doxygen.postgresql.org/clauses_8c.html#ac91c4055a7eb3aa6f1bc104479464b28
> (in this case, for example if you have a predicate A=5 then you can basically
> substitute in A=5 for any expression higher up in the the plan).
> Other classic optimizations include things such as `A OR TRUE` --> `A`, `A
> AND TRUE` --> TRUE, etc.
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