zabetak commented on code in PR #4505:
URL: https://github.com/apache/calcite/pull/4505#discussion_r2487071007
##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -488,9 +493,13 @@ private RexNode simplifyMultiply(RexCall e) {
}
private RexNode simplifyDivide(RexCall e) {
- final int oneIndex = findLiteralIndex(e.operands, BigDecimal.ONE);
- if (oneIndex == 1) {
- RexNode leftOperand = e.getOperands().get(0);
+ RexNode leftOperand = e.getOperands().get(0);
+ RexNode rightOperand = e.getOperands().get(1);
+ if ((isSafeExpression(leftOperand) && STRONG.isNull(leftOperand))
Review Comment:
OK, I checked the code in `RexSimplify#simplify(RexNode, RexUnknownAs)` and
I realized that we handle arithmetic with nulls there. However, I feel that
`NULL / y` to `NULL` is generally a "missed" simplification and not really
relevant to the denominator being zero or not.
I am a bit puzzled with the changes here cause there is a bit of overlap
with the code in
[SafeRexVisitor#visitCall](https://github.com/apache/calcite/blob/67e5bfcdc0151aa1926fa369382d12fc672ca5bf/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L1559).
It seems that the case `X / NULL` is handled via the `SafeRexVisitor` while
`NULL / X` is handled here. Shouldn't we handle both cases with the same code?
Which is the best place to do it?
##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -1189,6 +1102,23 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs
unknownAs) {
}
}
return RexUtil.composeDisjunction(rexBuilder, operands, false);
+ case CUSTOM:
+ if (a.getKind() == SqlKind.DIVIDE) {
+ RexNode op0 = ((RexCall) a).getOperands().get(0);
+ RexNode op1 = ((RexCall) a).getOperands().get(1);
+ if (RexUtil.isNull(op0) || RexUtil.isNull(op1)) {
+ return rexBuilder.makeLiteral(true);
+ }
+ if (!op1.isA(SqlKind.LITERAL)) {
+ return rexBuilder.makeCall(SqlStdOperatorTable.IS_NULL,
simplifyGenericNode((RexCall) a));
+ }
+ if (checkLiteralValue(op1, BigDecimal.ZERO)) {
+ return rexBuilder.makeCall(SqlStdOperatorTable.IS_NULL,
simplifyGenericNode((RexCall) a));
+ }
+ // op1 is a non-null and non-zero literal, so simplify op0
+ return simplifyIsNull(op0);
+ }
+ return null;
Review Comment:
I was mainly referring to the new code that is added but if we want to do
something more ambitious indeed we can post-pone to CALCITE-7263.
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