[FLINK-22341][hive] Fix describe table for hive dialect

This closes apache#15660

Author: lirui-apache

flink-connectors/flink-connector-hive/src/main/java/org/apache/flink/table/planner/delegation/hive/parse/HiveParserDDLSemanticAnalyzer.java

@@ -1153,7 +1153,7 @@ private Serializable analyzeDescribeTable(HiveParserASTNode ast) throws Semantic
         if (partSpec != null) {
             handleUnsupportedOperation("DESCRIBE PARTITION is not supported");
         }
-        if (colPath != null) {
+        if (!colPath.equals(tableName)) {
             handleUnsupportedOperation("DESCRIBE COLUMNS is not supported");
         }
 

flink-connectors/flink-connector-hive/src/test/java/org/apache/flink/connectors/hive/HiveDialectITCase.java

@@ -28,10 +28,12 @@
 import org.apache.flink.table.api.internal.TableEnvironmentInternal;
 import org.apache.flink.table.catalog.CatalogPartitionSpec;
 import org.apache.flink.table.catalog.CatalogTable;
+import org.apache.flink.table.catalog.ObjectIdentifier;
 import org.apache.flink.table.catalog.ObjectPath;
 import org.apache.flink.table.catalog.hive.HiveCatalog;
 import org.apache.flink.table.catalog.hive.HiveTestUtils;
 import org.apache.flink.table.delegation.Parser;
+import org.apache.flink.table.operations.DescribeTableOperation;
 import org.apache.flink.table.operations.command.ClearOperation;
 import org.apache.flink.table.operations.command.HelpOperation;
 import org.apache.flink.table.operations.command.QuitOperation;
@@ -255,6 +257,27 @@ public void testCreateTable() throws Exception {
         tableEnv.executeSql("create table if not exists tbl5 (m map<bigint,string>)");
         hiveTable = hiveCatalog.getHiveTable(new ObjectPath("default", "tbl5"));
         assertEquals(createdTimeForTableExists, hiveTable.getCreateTime());
+
+        // test describe table
+        Parser parser = ((TableEnvironmentInternal) tableEnv).getParser();
+        DescribeTableOperation operation =
+                (DescribeTableOperation) parser.parse("desc tbl1").get(0);
+        assertFalse(operation.isExtended());
+        assertEquals(
+                ObjectIdentifier.of(hiveCatalog.getName(), "default", "tbl1"),
+                operation.getSqlIdentifier());
+
+        operation = (DescribeTableOperation) parser.parse("describe default.tbl2").get(0);
+        assertFalse(operation.isExtended());
+        assertEquals(
+                ObjectIdentifier.of(hiveCatalog.getName(), "default", "tbl2"),
+                operation.getSqlIdentifier());
+
+        operation = (DescribeTableOperation) parser.parse("describe extended tbl3").get(0);
+        assertTrue(operation.isExtended());
+        assertEquals(
+                ObjectIdentifier.of(hiveCatalog.getName(), "default", "tbl3"),
+                operation.getSqlIdentifier());
     }
 
     @Test