lvheyang edited a comment on issue #723:
URL:
https://github.com/apache/arrow-datafusion/issues/723#issuecomment-883007802
For now I have just found 2 bad cases:
1. `select c0, ABS(c0 - 251.10794896957802) from foo where ABS(c0 -
251.10794896957802) < 111;`
2. `select c0, (250-c0) > 0 from foo where (250-c0) > 0`
The common point is that `abs(col) ` and `-1 * col` reverse the
monotonicity of the column. Such complex expressions are really hard to deal
with. ><
> 2. Limit to pruning simple expressions
To accomplish this target, I plan to limit pruning only to such simple
expressions
1. column with boolean type
2. simple arithmetic (`+ - * /`) and comparison (`> = < >= <= !=`)
expression, before we generating predicate, we should normalize the expression
to such form:
* `a * left(col) compare right(literal expression) ` where `a > 0`
3. compound logical relation (and or not), may consist of one or many
expressions
which we may not support by now:
1. scalar functions act on columns
2. expressions with 2 or more columns
This plan is not the final version, it may be changed since I encountered
difficulties.
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