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[CALCITE-7122] Eliminate nested calls for idempotent unary functions UPPER/LOWER/ABS/INITCAP/CEIL/FLOOR #4488

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[CALCITE-7122] Eliminate nested calls for idempotent unary functions UPPER/LOWER/ABS/INITCAP/CEIL/FLOOR #4488

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974f5f1
[CALCITE-7122] Eliminate nested calls for idempotent unary functions …
xuzifu666 Aug 1, 2025
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xuzifu666 Aug 11, 2025
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8 changes: 8 additions & 0 deletions core/src/main/java/org/apache/calcite/rex/RexInterpreter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -368,6 +368,14 @@ private static Comparable ceil(RexCall call, List<Comparable> values) {
if (values.get(0) == N) {
return N;
}
if (values.size() == 1) {
if (values.get(0) instanceof BigDecimal) {
BigDecimal bigDecimal = (BigDecimal) values.get(0);
return bigDecimal.longValue();
} else {
return values.get(0);
}
}
final Long v = (Long) values.get(0);
final TimeUnitRange unit = (TimeUnitRange) values.get(1);
switch (unit) {
Expand Down
43 changes: 38 additions & 5 deletions core/src/main/java/org/apache/calcite/rex/RexSimplify.java
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Expand Up @@ -88,6 +88,14 @@ public class RexSimplify {

private static final Strong STRONG = new Strong();

private static final ImmutableList<SqlOperator> IDEMOTENT_UNARY_FUNCTIONS =
ImmutableList.of(SqlStdOperatorTable.UPPER,
SqlStdOperatorTable.LOWER,
SqlStdOperatorTable.INITCAP,
SqlStdOperatorTable.ABS,
SqlStdOperatorTable.FLOOR,
SqlStdOperatorTable.CEIL);

/**
* Creates a RexSimplify.
*
Expand Down Expand Up @@ -333,7 +341,8 @@ RexNode simplify(RexNode e, RexUnknownAs unknownAs) {
return simplifyM2v((RexCall) e);
default:
if (e.getClass() == RexCall.class) {
return simplifyGenericNode((RexCall) e);
RexCall rexCall = (RexCall) e;
return simplifyIdempotentUnaryFunction(rexCall);
} else {
return e;
}
Expand Down Expand Up @@ -397,6 +406,30 @@ RexNode isFalse(RexNode e) {
: rexBuilder.makeCall(SqlStdOperatorTable.IS_FALSE, e);
}

/**
* Runs simplification unary function by eliminating idempotent.
*
* <p>Examples:
* <ul>
*
* <li>{@code abs(abs(abs(n))} returns {@code abs(n)}
*
* </ul>
*/
private RexNode simplifyIdempotentUnaryFunction(RexCall rexCall) {
while (IDEMOTENT_UNARY_FUNCTIONS.contains(rexCall.getOperator())
&& rexCall.getOperands().get(0) instanceof RexCall) {
RexCall subRexCall = (RexCall) rexCall.getOperands().get(0);
if (rexCall.getOperator() == subRexCall.getOperator()
&& rexCall.operands.size() == subRexCall.operands.size()) {
rexCall = subRexCall;
} else {
break;
}
}
return simplifyGenericNode(rexCall);
}

/**
* Runs simplification inside a non-specialized node.
*/
Expand Down Expand Up @@ -2373,7 +2406,7 @@ && sameTypeOrNarrowsNullability(e.getType(), intExpr.getType())) {
private RexNode simplifyCeilFloor(RexCall e) {
if (e.getOperands().size() != 2) {
// Bail out since we only simplify floor <date>
return e;
return simplifyIdempotentUnaryFunction(e);
}
final RexNode operand = simplify(e.getOperands().get(0), UNKNOWN);
if (e.getKind() == operand.getKind()) {
Expand All @@ -2382,7 +2415,7 @@ private RexNode simplifyCeilFloor(RexCall e) {
final RexCall child = (RexCall) operand;
if (child.getOperands().size() != 2) {
// Bail out since we only simplify ceil/floor <date>
return e;
return simplifyIdempotentUnaryFunction(e);
}
final RexLiteral parentFlag = (RexLiteral) e.operands.get(1);
final TimeUnitRange parentFlagValue = (TimeUnitRange) parentFlag.getValue();
Expand All @@ -2391,12 +2424,12 @@ private RexNode simplifyCeilFloor(RexCall e) {
if (parentFlagValue != null && childFlagValue != null) {
if (canRollUp(parentFlagValue.startUnit, childFlagValue.startUnit)) {
return e.clone(e.getType(),
ImmutableList.of(child.getOperands().get(0), parentFlag));
ImmutableList.of(simplify(child.getOperands().get(0)), parentFlag));
}
}
}
return e.clone(e.getType(),
ImmutableList.of(operand, e.getOperands().get(1)));
ImmutableList.of(simplify(operand), e.getOperands().get(1)));
}

/** Simplify TRIM function by eliminating nested duplication.
Expand Down
88 changes: 88 additions & 0 deletions core/src/test/java/org/apache/calcite/test/RexImplicationCheckerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
import org.apache.calcite.rex.RexSimplify;
import org.apache.calcite.rex.RexUnknownAs;
import org.apache.calcite.sql.SqlKind;
import org.apache.calcite.sql.SqlOperator;
import org.apache.calcite.sql.fun.SqlStdOperatorTable;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.calcite.util.DateString;
Expand All @@ -35,9 +36,13 @@

import org.junit.jupiter.api.Test;

import java.util.Arrays;
import java.util.List;

import static org.apache.calcite.test.RexImplicationCheckerFixtures.Fixture;

import static org.hamcrest.CoreMatchers.is;
import static org.hamcrest.CoreMatchers.not;
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.hasToString;

Expand Down Expand Up @@ -361,6 +366,89 @@ public class RexImplicationCheckerTest {
hasToString("2014"));
}

/** Test case for
* <a href="https://issues.apache.org/jira/browse/CALCITE-7122">[CALCITE-7122]
* Eliminate nested calls for idempotent unary functions UPPER/LOWER/ABS/INITCAP/CEIL/FLOOR</a>.
* */
@Test void testSimplifyIdempotentUnaryFunctions() {
// Test that:
// upper(upper(x)) is simplied to upper(x)
// lower(lower(x)) is simplied to lower(x)
// initcap(initcap(x)) is simplied to initcap(x)
final Fixture f = new Fixture();
List<SqlOperator> testOeratorList =
Arrays.asList(SqlStdOperatorTable.UPPER,
SqlStdOperatorTable.LOWER,
SqlStdOperatorTable.INITCAP);
for (SqlOperator operator : testOeratorList) {
RexCall innerCall =
(RexCall) f.rexBuilder
.makeCall(operator, f.rexBuilder.makeLiteral("Calcite Test"));
RexCall outerCall =
(RexCall) f.rexBuilder.makeCall(operator, innerCall);
RexCall simplifiedInnerCall =
(RexCall) f.simplify.simplifyPreservingType(outerCall,
RexUnknownAs.UNKNOWN, true);

assertThat(((RexLiteral) simplifiedInnerCall.getOperands().get(0))
.getValue(),
is(((RexLiteral) innerCall.getOperands().get(0)).getValue()));
}

// Test that:
// floor(floor(x)) is simplied to floor(x)
// ceil(ceil(x)) is simplied to ceil(x)
// abs(abs(x)) is simplied to abs(x)
testOeratorList =
Arrays.asList(SqlStdOperatorTable.ABS,
SqlStdOperatorTable.FLOOR,
SqlStdOperatorTable.CEIL);
for (SqlOperator operator : testOeratorList) {
RelDataType intType = f.rexBuilder.getTypeFactory().createSqlType(SqlTypeName.DECIMAL);
RexCall innerCall =
(RexCall) f.rexBuilder
.makeCall(operator, f.rexBuilder.makeLiteral(12, intType));
RexCall outerCall =
(RexCall) f.rexBuilder
.makeCall(operator, innerCall);
RexCall simplifiedInnerCall =
(RexCall) f.simplify.simplifyPreservingType(outerCall,
RexUnknownAs.UNKNOWN, true);
assertThat(((RexLiteral) simplifiedInnerCall.getOperands().get(0)).getValue(),
is(((RexLiteral) innerCall.getOperands().get(0)).getValue()));
}

// Test that max(abs(abs(x))) is simplied to max(abs(x))
RelDataType intType = f.rexBuilder.getTypeFactory().createSqlType(SqlTypeName.INTEGER);
RexCall innerCall =
(RexCall) f.rexBuilder
.makeCall(SqlStdOperatorTable.ABS, f.rexBuilder.makeLiteral(12, intType));
RexCall outerCall =
(RexCall) f.rexBuilder
.makeCall(SqlStdOperatorTable.ABS, innerCall);
RexCall maxCall =
(RexCall) f.rexBuilder
.makeCall(SqlStdOperatorTable.MAX, outerCall);
RexCall simplifiedInnerCall =
(RexCall) f.simplify.simplifyPreservingType(maxCall,
RexUnknownAs.UNKNOWN, true);
assertThat(simplifiedInnerCall.getOperator(), is(SqlStdOperatorTable.MAX));
assertThat(simplifiedInnerCall.getOperands().get(0), is(innerCall));
assertThat(simplifiedInnerCall.getOperands().get(0), not(outerCall));

// negative test
innerCall = (RexCall) f.rexBuilder
.makeCall(SqlStdOperatorTable.UPPER, f.rexBuilder.makeLiteral("Calcite Test"));
outerCall = (RexCall) f.rexBuilder.makeCall(SqlStdOperatorTable.LOWER, innerCall);
simplifiedInnerCall = (RexCall) f.simplify
.simplifyPreservingType(outerCall, RexUnknownAs.UNKNOWN, true);

assertThat(simplifiedInnerCall.getOperands().get(0),
not(((RexLiteral) innerCall.getOperands().get(0)).getValue()));
assertThat(((RexCall) simplifiedInnerCall.getOperands().get(0)).getOperands().get(0),
is(innerCall.getOperands().get(0)));
}

/** Test case for
* <a href="https://issues.apache.org/jira/browse/CALCITE-7042">[CALCITE-7042]
* Eliminate nested TRIM calls, exploiting the fact that TRIM is idempotent</a>. */
Expand Down
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