Vladimir Sitnikov created CALCITE-2449:
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Summary: RexSimplify overhaul
Key: CALCITE-2449
URL: https://issues.apache.org/jira/browse/CALCITE-2449
Project: Calcite
Issue Type: Improvement
Components: core
Affects Versions: 1.17.0
Reporter: Vladimir Sitnikov
Assignee: Julian Hyde
I would like to update \{{RexSimplify}} as follows:
1) Avoid multiple passes over the same expressions. Current logic calls
"simplify" in multiple places, and it might cause simplification of the same
tree again and again.
2) I would like to rework \{{unknownAsFalse}} into support for \{{IS TRUE}}.
Current support for \{{unknownAsFalse}} is hard to follow, and it looks like
IS_TRUE(expr) allows for the same optimizations. In other words,
"unknownAsFalse" would become a silent adding of IS_TRUE on top of the input
expression. Then rules like \{{OR(x, y) IS TRUE ==> x IS TRUE or y IS TRUE}}
would push \{{IS TRUE}} downstream.
3) I would like to "reorder" predicates in a defined order (e.g. rewrite \{{5=x
==> x=5}} or \{{(x=1 or y=2) and (z=3)}} ==> \{{(z=3) and (x=1 or y=2)}}. It
looks like adding \{{int nodeCount;}} to \{{RexNode}} would be helpful to rank
rex nodes.
4) There are other bugs identified by expression fuzzer (like {{and(null,
not(null))}} conversion to true and so on)
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