Added SHOW TABLES and DESCRIBE table support

pinot-common/src/main/java/org/apache/pinot/common/function/scalar/ArrayFunctions.java

@@ -305,4 +305,48 @@ public static Object arrayValueConstructor(Object... arr) {
     }
     return arr;
   }
+
+  @ScalarFunction
+  public static int[] generateIntArray(int start, int end, int inc) {
+    int size = (end - start) / inc + 1;
+    int[] arr = new int[size];
+
+    for (int i = 0, value = start; i < size; i++, value += inc) {
+      arr[i] = value;
+    }
+    return arr;
+  }
+
+  @ScalarFunction
+  public static long[] generateLongArray(long start, long end, long inc) {
+    int size = (int) ((end - start) / inc + 1);
+    long[] arr = new long[size];
+
+    for (int i = 0; i < size; i++, start += inc) {
+      arr[i] = start;
+    }
+    return arr;
+  }
+
+  @ScalarFunction
+  public static float[] generateFloatArray(float start, float end, float inc) {
+    int size = (int) ((end - start) / inc + 1);
+    float[] arr = new float[size];
+
+    for (int i = 0; i < size; i++, start += inc) {
+      arr[i] = start;
+    }
+    return arr;
+  }
+
+  @ScalarFunction
+  public static double[] generateDoubleArray(double start, double end, double inc) {
+    int size = (int) ((end - start) / inc + 1);
+    double[] arr = new double[size];
+
+    for (int i = 0; i < size; i++, start += inc) {
+      arr[i] = start;
+    }
+    return arr;
+  }
 }

pinot-common/src/main/java/org/apache/pinot/sql/parsers/parser/SqlShowTables.java

@@ -0,0 +1,52 @@
+/**
+ * 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.pinot.sql.parsers.parser;
+
+import java.util.List;
+import org.apache.calcite.sql.SqlCall;
+import org.apache.calcite.sql.SqlKind;
+import org.apache.calcite.sql.SqlNode;
+import org.apache.calcite.sql.SqlOperator;
+import org.apache.calcite.sql.SqlSpecialOperator;
+import org.apache.calcite.sql.SqlWriter;
+import org.apache.calcite.sql.parser.SqlParserPos;
+
+public class SqlShowTables extends SqlCall {
+
+  private static final SqlSpecialOperator OPERATOR = new SqlSpecialOperator("UDF", SqlKind.OTHER);
+
+  protected SqlShowTables(SqlParserPos pos) {
+    super(pos);
+  }
+
+  @Override public SqlOperator getOperator() {
+    return OPERATOR;
+  }
+
+  @Override
+  public List<SqlNode> getOperandList() {
+    return List.of();
+  }
+
+  @Override
+  public void unparse(SqlWriter writer, int leftPrec, int rightPrec) {
+    UnparseUtils u = new UnparseUtils(writer, leftPrec, rightPrec);
+    u.keyword("SHOW", "TABLES");
+  }
+}

pinot-common/src/test/java/org/apache/pinot/common/function/FunctionDefinitionRegistryTest.java

@@ -42,8 +42,8 @@ public class FunctionDefinitionRegistryTest {
   private static final List<String> IGNORED_FUNCTION_NAMES = ImmutableList.of(
       // Geo functions are defined in pinot-core
       "geotoh3",
-      // ArrayToMV and ArrayValueConstructor are placeholder functions without implementation
-      "arraytomv", "arrayvalueconstructor",
+      // ArrayToMV, ArrayValueConstructor and GenerateArray are placeholder functions without implementation
+      "arraytomv", "arrayvalueconstructor", "generatearray",
       // Scalar function
       "scalar",
       // Functions without scalar function counterpart as of now