HIVE-27193: Fix catalog parsing bug and verify all provided edge cases in parseDbName

Author: ashniku

standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/utils/MetaStoreUtils.java

@@ -1100,6 +1100,9 @@ public static String[] parseDbName(String dbName, Configuration conf) {
     }
     if (hasCatalogName(dbName)) {
       String[] names = dbName.substring(1).split(CATALOG_DB_SEPARATOR, 2);
+      if (names.length == 1) {
+        return new String[] {names[0], null};
+      }
       if (names[1].isEmpty()) {
         names[1] = null;
       } else if (names[1].equals(DB_EMPTY_MARKER)) {

standalone-metastore/metastore-server/src/test/java/org/apache/hadoop/hive/metastore/utils/TestMetastoreUtilsParseDbName.java

@@ -38,6 +38,17 @@ public void testParseDbNameEdgeCases() {
     assertArrayEquals(new String[]{"hive", "@!"}, parseDbName("@!", conf));
     assertArrayEquals(new String[]{"", null}, parseDbName("@#", conf));
     assertArrayEquals(new String[]{"", "db1"}, parseDbName("@#db1", conf));
+    assertArrayEquals(new String[]{"cat1", null}, parseDbName("@cat1", conf));
+    assertArrayEquals(new String[]{"cat1", null}, parseDbName("@cat1#", conf));
+    assertArrayEquals(new String[]{"cat1", ""}, parseDbName("@cat1#!", conf));
+    assertArrayEquals(new String[]{"cat1", "@db1"}, parseDbName("@cat1#@db1", conf));
+    assertArrayEquals(new String[]{"cat1", "#db1"}, parseDbName("@cat1##db1", conf));
+    assertArrayEquals(new String[]{"cat1", "db1"}, parseDbName("@cat1#db1", conf));
+    assertArrayEquals(new String[]{"cat1", "db1!"}, parseDbName("@cat1#db1!", conf));
+    assertArrayEquals(new String[]{"cat1!", null}, parseDbName("@cat1!", conf));
+    assertArrayEquals(new String[]{"hive", "#db1"}, parseDbName("#db1", conf));
+    assertArrayEquals(new String[]{"hive", "#!"}, parseDbName("#!", conf));
+    assertArrayEquals(new String[]{"hive", "#"}, parseDbName("#", conf));
     assertArrayEquals(new String[]{"hive", "@cat1"}, parseDbName("@cat1", conf));
     assertArrayEquals(new String[]{"cat1", null}, parseDbName("@cat1#", conf));
     assertArrayEquals(new String[]{"cat1", ""}, parseDbName("@cat1#!", conf));