Add SQL DIV function. (#16464)

* Add SQL DIV function.

This function has been documented for some time, but lacked a binding,
so it wasn't usable.

* Add a case with two expression inputs.

sql/src/main/java/org/apache/druid/sql/calcite/expression/builtin/DivOperatorConversion.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.druid.sql.calcite.expression.builtin;
+
+import org.apache.calcite.sql.SqlFunctionCategory;
+import org.apache.calcite.sql.SqlOperator;
+import org.apache.calcite.sql.type.InferTypes;
+import org.apache.calcite.sql.type.OperandTypes;
+import org.apache.calcite.sql.type.SqlTypeName;
+import org.apache.druid.sql.calcite.expression.DirectOperatorConversion;
+import org.apache.druid.sql.calcite.expression.OperatorConversions;
+
+public class DivOperatorConversion extends DirectOperatorConversion
+{
+  private static final SqlOperator SQL_OPERATOR =
+      OperatorConversions
+          .operatorBuilder("DIV")
+          .operandTypeChecker(OperandTypes.DIVISION_OPERATOR)
+          .operandTypeInference(InferTypes.FIRST_KNOWN)
+          .returnTypeCascadeNullable(SqlTypeName.BIGINT)
+          .functionCategory(SqlFunctionCategory.NUMERIC)
+          .build();
+
+  public DivOperatorConversion()
+  {
+    super(SQL_OPERATOR, "div");
+  }
+}

sql/src/main/java/org/apache/druid/sql/calcite/planner/DruidOperatorTable.java

@@ -81,6 +81,7 @@
 import org.apache.druid.sql.calcite.expression.builtin.ContainsOperatorConversion;
 import org.apache.druid.sql.calcite.expression.builtin.DateTruncOperatorConversion;
 import org.apache.druid.sql.calcite.expression.builtin.DecodeBase64UTFOperatorConversion;
+import org.apache.druid.sql.calcite.expression.builtin.DivOperatorConversion;
 import org.apache.druid.sql.calcite.expression.builtin.ExtractOperatorConversion;
 import org.apache.druid.sql.calcite.expression.builtin.FloorOperatorConversion;
 import org.apache.druid.sql.calcite.expression.builtin.GreatestOperatorConversion;
@@ -369,6 +370,7 @@ public class DruidOperatorTable implements SqlOperatorTable
                    .add(new AliasedOperatorConversion(CHARACTER_LENGTH_CONVERSION, "STRLEN"))
                    .add(new DirectOperatorConversion(SqlStdOperatorTable.CONCAT, "concat"))
                    .add(new DirectOperatorConversion(SqlStdOperatorTable.EXP, "exp"))
+                   .add(new DivOperatorConversion())
                    .add(new DirectOperatorConversion(SqlStdOperatorTable.DIVIDE_INTEGER, "div"))
                    .add(new DirectOperatorConversion(SqlStdOperatorTable.LN, "log"))
                    .add(new DirectOperatorConversion(SqlStdOperatorTable.LOWER, "lower"))

sql/src/test/java/org/apache/druid/sql/calcite/CalciteQueryTest.java

@@ -602,6 +602,38 @@ public void testSafeDivide()
     );
   }
 
+  @Test
+  public void testDiv()
+  {
+    cannotVectorize();
+    final Map<String, Object> context = new HashMap<>(QUERY_CONTEXT_DEFAULT);
+
+    testQuery(
+        "select cnt, m1, div(m1, 2), div(cnt+2, cnt+1) from foo",
+        context,
+        ImmutableList.of(
+            newScanQueryBuilder()
+                .dataSource(CalciteTests.DATASOURCE1)
+                .intervals(querySegmentSpec(Filtration.eternity()))
+                .virtualColumns(
+                    expressionVirtualColumn("v0", "div(\"m1\",2)", ColumnType.LONG),
+                    expressionVirtualColumn("v1", "div((\"cnt\" + 2),(\"cnt\" + 1))", ColumnType.LONG)
+                )
+                .columns(ImmutableList.of("cnt", "m1", "v0", "v1"))
+                .context(QUERY_CONTEXT_DEFAULT)
+                .build()
+        ),
+        ImmutableList.of(
+            new Object[]{1L, 1.0f, 0L, 1L},
+            new Object[]{1L, 2.0f, 1L, 1L},
+            new Object[]{1L, 3.0f, 1L, 1L},
+            new Object[]{1L, 4.0f, 2L, 1L},
+            new Object[]{1L, 5.0f, 2L, 1L},
+            new Object[]{1L, 6.0f, 3L, 1L}
+        )
+    );
+  }
+
   @Test
   public void testGroupByLimitWrappingOrderByAgg()
   {