zabetak commented on code in PR #4505:
URL: https://github.com/apache/calcite/pull/4505#discussion_r2485912671
##########
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:
The code handling the division here is very similar to the code inside
`simplifyIsNotNull` so I am wondering if it's worth refactoring it into a
separate private method.
##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -1140,9 +1037,23 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs
unknownAs) {
switch (a.getKind()) {
case LITERAL:
return rexBuilder.makeLiteral(!((RexLiteral) a).isNull());
+ case 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(false);
+ }
Review Comment:
If we handle simplifications of arithmetic operations with nulls this code
seems redundant and it might be unreachable. For instance, if `simplifyDivide`
is able to transform `x/null` and `null/y` to `null` then I guess we cannot hit
this path.
##########
core/src/main/java/org/apache/calcite/plan/Strong.java:
##########
@@ -356,7 +358,8 @@ private static Map<SqlKind, Policy> createPolicyMap() {
map.put(SqlKind.CHECKED_TIMES, Policy.ANY);
map.put(SqlKind.CHECKED_DIVIDE, Policy.ANY);
Review Comment:
Wondering if we should also handle `CHECKED_DIVIDE` with the same custom
policy.
##########
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:
This appears to be somewhat "new" simplification logic that was not there
before. I get the feeling that simplifications of arithmetic operations with
nulls is a problem that we should tackle in a more general fashion and not only
for the division operator. From my point of view this deserves a separate JIRA
ticket and PR dedicated to simplification of arithmetic operations with nulls.
I see there is already some code doing this for comparison operators
(`simplifyComparisonWithNull`).
##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -1028,9 +1037,25 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs
unknownAs) {
switch (a.getKind()) {
case LITERAL:
return rexBuilder.makeLiteral(!((RexLiteral) a).isNull());
+ case 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(false);
+ }
+ if (!op1.isA(SqlKind.LITERAL)) {
+ return rexBuilder.makeCall(
+ SqlStdOperatorTable.IS_NOT_NULL, simplifyGenericNode((RexCall)
a));
+ }
+ if (checkLiteralValue(op1, BigDecimal.ZERO)) {
+ return rexBuilder.makeCall(
+ SqlStdOperatorTable.IS_NOT_NULL, simplifyGenericNode((RexCall)
a));
+ }
+ // op1 is a non-null and non-zero literal, so simplify op0
+ return simplifyIsNotNull(op0);
+ }
default:
- throw new AssertionError("every CUSTOM policy needs a handler, "
- + a.getKind());
+ return null;
Review Comment:
Actually, I suggested to not add a **new** Assertion in `simplifyIsNull`
method to avoid breaking changes. Removing the assertion from here for
consistency purposes makes sense but I wouldn't push hard on it especially if
others disagree.
##########
core/src/main/java/org/apache/calcite/rex/RexSimplify.java:
##########
@@ -415,17 +415,22 @@ private RexNode simplifyGenericNode(RexCall e) {
*/
private static int findLiteralIndex(List<RexNode> operands, BigDecimal
value) {
for (int i = 0; i < operands.size(); i++) {
- if (operands.get(i).isA(SqlKind.LITERAL)) {
- Comparable comparable = ((RexLiteral) operands.get(i)).getValue();
- if (comparable instanceof BigDecimal
- && value.compareTo((BigDecimal) comparable) == 0) {
- return i;
- }
+ if (checkLiteralValue(operands.get(i), value)) {
+ return i;
}
}
return -1;
}
+ /** Check whether the operand is a literal of the specified value. */
Review Comment:
It seems that this method will always return false for approximate numeric
(DOUBLE, FLOAT, REAL) literals since `comparable instanceof BigDecimal` is
`false`.
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