Add T_DIST scalar function

core/trino-main/src/main/java/io/trino/metadata/SystemFunctionBundle.java

@@ -125,6 +125,7 @@
 import io.trino.operator.scalar.ConcatWsFunction;
 import io.trino.operator.scalar.DataSizeFunctions;
 import io.trino.operator.scalar.DateTimeFunctions;
+import io.trino.operator.scalar.DistributionFunctions;
 import io.trino.operator.scalar.EmptyMapConstructor;
 import io.trino.operator.scalar.FailureFunction;
 import io.trino.operator.scalar.FormatNumberFunction;
@@ -441,6 +442,7 @@ public static FunctionBundle create(FeaturesConfig featuresConfig, TypeOperators
                 .scalars(BitwiseFunctions.class)
                 .scalars(DateTimeFunctions.class)
                 .scalar(DateTimeFunctions.FromUnixtimeNanosDecimal.class)
+                .scalars(DistributionFunctions.class)
                 .scalars(JsonFunctions.class)
                 .scalars(JsonInputFunctions.class)
                 .scalars(JsonOutputFunctions.class)

core/trino-main/src/main/java/io/trino/operator/scalar/DistributionFunctions.java

@@ -0,0 +1,41 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.trino.operator.scalar;
+
+import io.trino.spi.TrinoException;
+import io.trino.spi.function.ScalarFunction;
+import io.trino.spi.function.SqlType;
+import org.apache.commons.math3.distribution.TDistribution;
+
+import static io.trino.spi.StandardErrorCode.INVALID_FUNCTION_ARGUMENT;
+import static io.trino.spi.type.StandardTypes.BOOLEAN;
+import static io.trino.spi.type.StandardTypes.DOUBLE;
+import static io.trino.spi.type.StandardTypes.INTEGER;
+
+public class DistributionFunctions
+{
+    private DistributionFunctions() {}
+
+    @ScalarFunction("t_dist")
+    @SqlType(DOUBLE)
+    public static double tDistribution(@SqlType(DOUBLE) double x, @SqlType(INTEGER) long degreesOfFreedom, @SqlType(BOOLEAN) boolean cumulative)
+    {
+        if (degreesOfFreedom < 1) {
+            throw new TrinoException(INVALID_FUNCTION_ARGUMENT, "degrees_of_freedom must be greater than or equal to 1");
+        }
+
+        TDistribution tDistribution = new TDistribution(degreesOfFreedom);
+        return cumulative ? tDistribution.cumulativeProbability(x) : tDistribution.density(x);
+    }
+}

core/trino-main/src/test/java/io/trino/operator/scalar/TestDistributionFunctions.java

@@ -0,0 +1,57 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.trino.operator.scalar;
+
+import io.trino.sql.query.QueryAssertions;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.parallel.Execution;
+
+import static io.trino.testing.assertions.TrinoExceptionAssert.assertTrinoExceptionThrownBy;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS;
+import static org.junit.jupiter.api.parallel.ExecutionMode.CONCURRENT;
+
+@TestInstance(PER_CLASS)
+@Execution(CONCURRENT)
+public class TestDistributionFunctions
+{
+    private QueryAssertions assertions;
+
+    @BeforeAll
+    public void init()
+    {
+        assertions = new QueryAssertions();
+    }
+
+    @AfterAll
+    public void teardown()
+    {
+        assertions.close();
+        assertions = null;
+    }
+
+    @Test
+    public void testTDist()
+    {
+        assertThat(assertions.function("t_dist", "60", "1", "true"))
+                .isEqualTo(0.9946953263673767);
+        assertThat(assertions.function("t_dist", "8", "3", "false"))
+                .isEqualTo(7.369065209469264E-4);
+        assertTrinoExceptionThrownBy(assertions.function("t_dist", "60", "0", "true")::evaluate)
+                .hasMessage("degrees_of_freedom must be greater than or equal to 1");
+    }
+}